<![CDATA[NBC Connecticut - Connecticut Weather News and Coverage - On Ryan's Radar]]>Copyright 2019http://www.nbcconnecticut.com/weather/storiesen-usMon, 14 Oct 2019 03:54:01 -0400Mon, 14 Oct 2019 03:54:01 -0400NBC Local Integrated Media<![CDATA[July 2019 Set to Break Record]]>513366451Mon, 29 Jul 2019 21:14:09 -0400https://media.nbcconnecticut.com/images/213*120/Model+iCast+Future++Feels+Like+Temp+CT.png

With two days left in July it appears as if we will come close to breaking the record for the warmest month in the 114-year period of weather records in the Hartford area. The current record holder is July 2013 with an average temperature of 77.9 degrees. As of today we are at 78.0 degrees and based on the forecast we should tack on an additional one or two tenths Tuesday. We will likely lose a tenth of two of a degree on Wednesday.

This is not a surprise as the summers are becoming warmer and warmer. Since 1970 summers gave warmed aprpoximately 1 degree locally - while the warming over the United States as a whole is close to two degrees. 

So far July has featured 17 days at or above 90 degrees with tomorrow virtually a lock for 90 again. That will be a record breaking 18 days of 90 degree heat for the month of July in the Hartford area which is a record. Last August was the second warmest August on record.

With the heat and humidity comes the risk for strong to severe thunderstorms on Wednesday.

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<![CDATA[Incredible Cape Cod Tornado]]>513116551Tue, 23 Jul 2019 20:19:04 -0400https://media.nbcconnecticut.com/images/214*120/67157713_2402704003351829_166124258357936128_o.jpg

An exceptionally unusual tornado struck the mid Cape today with substantial damage in parts of Yarmouth, Dennis, and Harwich. The storm formed along a warm front that was draped along the South Coast of New England. This is a classic setup for tornadoes along our shoreline.

The first sign of trouble was just after 9 a.m. when a supercell thunderstorm developed just south of the Hamptons. A supercell is a fancy term for a thunderstorm that is rotating. There certainly could have been a waterspout just off Long Island. The same storm tracked east-northeast toward Martha's Vineyard when the storm started to take off again. There was a very narrow corridor when moist and unstable air just offshore was juxtaposed with an area of strong low level wind shear over the Cape. Where the two intersected - along the warm front -  the rotating storm and tornado occured. 

This radar image shows the strong rotation moving through Yarmouth. In addition to a tornadic circulation there was a long swath of damaging wind that stretched from Mashpee east through Chatham and included a measured wind gust of 90 mph at Kalmus Beach in Hyannis!

I have a few annoying weather sayings in the summer for severe weather that I say all the time to anyone who will listen. "Always watch the triple point" and "south coast special" for events just like this. 

The National Weather Service did a masterful job with this tornado with timely warnings that included 18 minutes of lead time. Additionally, they recognized a suble signature on radar that indicated tornado debris had been sucked up into the storm's updraft which allowed them to confirm a tornado touchdown before any damage reports came in. 

Thankfully this has been an unsuually quiet severe weather season in New England with the exception of today's Cape Cod tornadoes. Let's keep it quiet through the fall!

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<![CDATA[Tornado Outbreak Was 30 Years Ago Today]]>512200552Wed, 10 Jul 2019 14:21:01 -0400https://media.nbcconnecticut.com/images/179*120/89-7-11-tornado.jpg

There are only a few “classic” northeastern U.S. tornado outbreaks that jump out in my mind. The 1985 Pennsylvania outbreak is one, the 1998 Pennsylvania/New York outbreak is another, and so is the 1989 northeast outbreak. The epicenter of that outbreak was right here in Connecticut with an F4 tornado touchdown in Hamden and New Haven.

The atmosphere couldn’t have been more primed for a big tornado event. Here’s the morning weather balloon launch and sounding from Albany.

A classic "elevated mixed layer" is present which is something almost always found in Kansas and Oklahoma before big tornado events. On July 10, 1989 that kind of explosive atmosphere was over Connecticut. What is also striking is the exceptional wind shear in the atmosphere. The wind rapidly strengthens and turns in a clockwise direction with height placing Connecticut in the cross hairs of a big event.

The first tornado touched down in upstate New York west of Albany and was on the ground for an incredible 42 miles. That same supercell went on to produce a series of tornadoes in Connecticut. The first tornado touched down near Route 4 in Cornwall and continued south into Bantam. The second tornado touched down in Watertown and Waterbury. The most violent of the tornadoes touched down in Hamden and continued south into New Haven.

The damage in Connecticut was substantial with hundreds and hundreds of homes and businesses destroyed. Many people in the New Haven suburbs – including North Haven and North Branford were caught in the hail core of the storm with golf ball size hail or larger. Southeast of where the tornado lifted in Newhallville substantial wind damage occurred with many of the pine trees near Lake Saltonstall on the Branford/East Haven line snapped in half.

There were other tornadoes that day – some in northern Massachuetts, others just west of Danbury in Putnam County, and another swarm in northern New Jersey. If we were able to look at radar data (which sadly, we cannot) we’d probably see a string of supercells draped across the region.

On a personal note, the 1989 tornado event is my first weather memory as a kid. At the time I was living in Branford but on vacation with my family on Cape Cod. When I heard about the tornado back home I was devastated! I couldn’t believe that I missed “the big one” back home. I'm not sure if the '89 tornado was what sparked my life-long love of weather but it's clear looking back that it helped solidify my dream of being a meteorologist.

Photo Credit: Hamden Fire Retirees
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<![CDATA[Big Afternoon Hail]]>509140731Fri, 26 Apr 2019 20:27:17 -0400https://media.nbcconnecticut.com/images/213*120/2_042619.jpg

At 2:30 this afternoon I was preparing to do a severe weather cut-in for large hail in Northeastern Connecticut when a tornado warning was issued. The storm was rotating fast a little more than a mile above our heads but closer to the ground the rotation was fairly minimal.

The atmosphere supported rotating thunderstorms today. We were forecasting hail with a brief surge in elevated instability and strong wind shear. As a storm spins an enhanced "updraft" develops which helps hail stones grow larger and larger. 

So why no tornado? The storm wasn't anchored near the ground. This storm was elevated - basically it was feeding off instability around a mile up. The atmosphere near the ground was very stable which would preclude tornado development - and also preclude strong winds from mixing to the ground. Hail, on the other hand, just has to rely on gravity. Gravity exists whether the air is stable or unstable so the hail stones fell to the ground readily and pelted Tolland, Stafford, and Willington. 

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<![CDATA[The April Fools' Blizzard]]>507976131Mon, 01 Apr 2019 23:02:12 -0400https://media.nbcconnecticut.com/images/213*120/April_1997_snowstorm_1200x675_1469258819993.jpg

April snowstorms are not that unusual in Connecticut. The April 6, 1982 blizzard was one of the most severe on record. Heavy snow, high winds, and lightning crushed the state with one to two feet of snow and gusts to 70 mph. Vivid lightning and thunder accompanied the snow along with unusually cold temperatures.

Fifteen years later it was the March 31-April 1, 1997 blizzard that crushed southern New England. 33.1" of snow well in Worcester with nearly that much in Boston. The snow was like concrete that shut down eastern Massachusetts for days. Locally, the storm wasn't that intense but was still a beast. 

21" of snow fell in Putnam and Norfolk with about a foot in the Hartford area. Along the shoreline there was a few inches right at the coast but just inland as much as a foot fell in some towns. 100,000 utility customers were knocked into darkness by the weight of the snow. 

<![CDATA[Ice Storm of 2019]]>504674621Mon, 21 Jan 2019 21:38:39 -0400https://media.nbcconnecticut.com/images/160*120/01211911.jpg

It was an impressive storm and a real challenge to forecast. One of the hardest parts of the forecast was figuring out which type of precipitation we'd see - snow, sleet, or freezing rain - and when the change in type would occur. 

The good news is that we were able to accurately toss most of the computer model solutions we saw because we knew there was a good chance they were far too warm. The sadly inaccurate GFS had temperatures reaching 50F in Hartford during the storm. The actual high was in the 20s. Just an abysmal performance. 

One of the most important parts of being a meteorlogist these days is knowing when to use which computer model. All of our models have different strengths, weaknesses, and uses. Not all are created equal! For example, low level temperature forecasts on America's flagship model, the GFS, are routinely off by 10 or 15 degrees in storms like this one. A 25F temperature bust is a new low for the model. Part of the reason is that these global models struggle with small scale features near the ground and come up with unrealistic solutions - like a surface low tracking over Hartford in this setup. The actual low tracked where one would expect it to - over the south shore of Long Island.

Our high resolution models - like the 3km NAM, the HRRR, and the HREF (an ensemble of a few high resolution models) did a very good job. Particular kudos go to the HREF. We relied heavily on these and were mentioning the potential for significant ice around New Haven the day before the storm when many models had 50s for the same area.

The one thing we did miss was the location of the biggest icing. While we did mention the New Haven area as a trouble spot I was highlighting the Farmington Valley and Litchfield Hills as one of the areas most at risk. The cold was so deep that almost all of what fell was snow than sleet - the more shallow cold air was displaced south of Hartford. 

It appears that between 1/2 and 3/4 inch of ice stuck to trees and power lines from Middletown west through Newtown. At the height of the storm more than 30,000 utility customers were without power including 100% of Bethany. 

There was damage as far south as New Haven - including downtown and East Rock. 

It was quite a storm. The snowfall forecast was OK (generally a bit too high - especially at the coast) but the forecast of a flash freeze and ice storm worked out well. Another good reminder that figuring out which models to use and which models to toss is probably the most important part of my job. 

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<![CDATA[Major Winter Storm This Weekend]]>504461011Wed, 16 Jan 2019 22:07:02 -0400https://media.nbcconnecticut.com/images/213*120/Snow+Type.png

Odds of a significant winter storm this weekend continue to increase and I'm quite confident we've got a mess on our hands Saturday night and Sunday. I'm expecting snow to develop across Connecticut between 7 p.m. and 11 p.m. Saturday and then the question is when do we see a transition to sleet and freezing rain? 

This storm is going to be loaded with juice. Moisture streaming up from the Gulf of Mexico means we're going to get a lot of precipitation. Most models show around 2" of melted precipitation - that's really significant. The plume diagram above from the GFS ensembles show the heavy amounts on virtually ever ensemble member. 

The storm is unlikely, however, to be all snow. While we can't rule out a snowier solution most of our computer models show a lot of warm air moving in aloft by Sunday morning. These two graphics (below) off the GFS computer model show the large tilt to this storm with height. At the surface the storm's center will be near Connecticut while about 10,000 above our heads the storm will actually be closer to Burlington, VT! This is a classic setup for cold air hanging on near the ground but milder air moving in at cloud level.

So we're left with the question of just how much cold air remains at the surface and how much warm air comes in aloft. A degree or two will make a big difference and 50 or 100 miles in storm track will too! The colder air residing under warmer clouds is a good combination for ice. Here's what's most likely at this moment. 


  • Accumulating snowfall down to the shoreline starting Saturday evening. 
  • Snow changes to sleet and freezing rain in most locations on Sunday.
  • Significant accumulations of snow, sleet, and freezing rain possible.
  • A narrow zone of significant icing (freezing rain) may cause issues for trees and power lines.
  • More specific storm totals and change over times are to be determined.
  • Challenging travel conditions will exist for a good chunk of Sunday. 
  • Bitterly cold moves in for Monday and any slush will freeze solid. 

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<![CDATA[Winter Shows Signs of Life]]>504190791Thu, 10 Jan 2019 22:09:15 -0400https://media.nbcconnecticut.com/images/160*120/gfs_t2maf_slp_conus2_5.png

Our warm beginning to January is coming to an end. Temperatures will be around or even a bit below normal for the next week. The question is will we get any snow?

This weekend's storm is a miss. As I mentioned in my post earlier this week the weather pattern is just not favorable for a snowstorm here. Sometimes hostile patterns can deliver snow but this one will not. 

By next weekend, however, it does appear the pattern begins to shift. We'll have cold air nearby and increasingly it looks like we'll be entering into a stormy regime. Both the GFS and European computer models have strong signals for storminess nearby in the Day 9 and Day 10 range. 

What has been a very consistent signal toward the end of the month and early February is the potential for a blockbuster pattern. This is the kind of pattern that tends to bring prolonged cold and big snow. It's a pattern that meteorologists drool over in New England. 

The big red blobs are areas of unusual warmth and large "blocks" in the atmosphere. The presence of the blocking over Greenland and the Arctic - when coupled with ridging over the western United States is the holy grail for Northeastern U.S. snow. These blocks tend to result in large undulations in the jet stream and are conducive to storm development off New England. 

Will this verify? Of course a 3 week forecast - even when you're just looking at a general pattern - is a tough one. But there are some things that make me think that this could actually happen. The biggest signal in my mind is unusually warm air in the stratosphere (the layer of the atmosphere above the troposphere about 12 miles over our heads) that is already in place and continues to show up over the next 10 days. This stratospheric warming can be a precursor to blocking over the Arctic and Greenland as that warm signal descends and winds up disrupting the Polar Vortex. The Pacific jet stream - that has flooded the country with warmth - appears to get shuffled quite a bit in the coming weeks. 

If you love winter - stay tuned. I don't think our snowless stretch will continue forever. If you hate the snow you may have a rough stretch coming up. We'll keep you posted. 

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<![CDATA[Weekend Storm? Maybe!]]>504027041Mon, 07 Jan 2019 21:32:32 -0400https://media.nbcconnecticut.com/images/160*120/gfs_pr6_slp_t850_neng_29.png

Last night's GFS computer model came in with a fun looking Sunday forecast. A blizzard for Southern New England! Will it happen? Maybe, but probably not. 

In the 5 or 6 day range it's better to use computer model ensembles as opposed to just one specific computer model run. As you go out in time a computer model's forecast becomes less and less accurate and its errors grow exponentially. The ensemble approach allows us to make small changes to a model's initial conditions and see the different outcomes that those changes produce. Sometimes solutions are tightly clustered and there's high confidence in a certain outcome. Other solutions can be wildly disparate which would imply a low confidence or uncertain forecast.

The GFS ensembles this afternoon show a wide spread. A bunch of possibilities none of which we can write off. Of course we have other computer models besides the GFS. The European model is even less bullish on the Sunday storm. Here's a different way to view ensemble data - by map. This is a look at the probability of >3" of snow at any given location based on the 50 European Ensemble members. For instance, if 25 of the 50 were dropping 3"+ of snow in Hartford the plotted probability would be 50%. 

So what to make of this? While the overall weather pattern turns colder it's not particularly favorable for a big snowstorm. That said, there is still the possibility that this storm could "thread the needle" and wind up developing in spite of a relatively hostile pattern for snow. It's happened before! The odds of seeing a snowstorm (over 6") remain low for now. We'll see what happens over the coming days. 

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<![CDATA[Where's Winter?]]>503928751Fri, 04 Jan 2019 21:45:38 -0400https://media.nbcconnecticut.com/images/160*123/ecmwf_apcp_f30_ne.png

9 times out of 10 a strengthening storm passing south of Long Island in early January would be something I'd be excited about. Gusty northerly winds at the surface keep the warmer marine air away and a nice conveyorbelt of moisture aloft rolls in from the ocean keeping the precipitation cranking. Not this time. The "perfect track" storm is missing one thing: cold air. There's none of it to be found here in New England.

A rainy Saturday with temperatures in the 30s. Dreadful weather. 

Beyond this weekend there are a few chances for more wintry weather. In fact, the weather pattern looks a bit colder toward the middle and end of next week. Two relatively weak systems move through Tuesday morning and Wednesday morning and both have the potential to produce some snow or mix - especially inland. It doesn't look like much. The European model shows odds of >1" of snow on Tuesday of about 50% in the Northwest Hills and less than 10% on the shoreline. That seems reasonable to me. 

The long range forecast in the 6-10 day window shows temperatures near normal here in New England. 

When will we get our first snowstorm of meteorological winter? I don't know. While things have been quiet since mid November I wouldn't write winter off. We've got a ways to go. 

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<![CDATA[2018: A Year of Weather Extremes]]>503732902Wed, 02 Jan 2019 20:22:45 -0400https://media.nbcconnecticut.com/images/213*120/2018_A_Year_of_Weather_Extremes.jpg

Chief Meteorologist Ryan Hanrahan takes a look back at the weather this year.]]>
<![CDATA[November Snowstorm]]>500977291Wed, 21 Nov 2018 00:00:15 -0400https://media.nbcconnecticut.com/images/213*120/November_Snowstorm_1200x675_1376541763616.jpg

A closer look at why roads were so bad during Thursday’s snowstorm. ]]>
<![CDATA[Siberian Cold for Thanksgiving]]>500975312Tue, 20 Nov 2018 23:44:08 -0400https://media.nbcconnecticut.com/images/213*120/Siberian_Cold_for_Thanksgiving_1200x675_1376504899834.jpg

Record cold is expected across Connecticut on Thanksgiving. ]]>
<![CDATA[Another Day of Tornadoes]]>498957901Mon, 29 Oct 2018 21:51:10 -0400https://media.nbcconnecticut.com/images/213*120/DqtVE8hXgAI7W9u1.jpg

Another remarkable tornado day in New England with three tornado touch downs this morning in Stonington, Woods Hole, and Fishers Island. The south coast of New England is not exactly a tornado hotspot but in an event like today's the south coast is favored. More on that in a minute.

The tornado over Fishers Island produced a path of widespread damage that included a home with virtually every window on three sides blown out. A shed was swept off its foundation and countless trees were snapped in half. A large tornado debris signature was detected by Doppler Radar as pieces of leaves and debris were sucked from the island up into the thunderstorm cloud. 

The tornado lifted over Fisher's Island Sound but the tornado touched down again on the Stonington/North Stonington line and continued on a discontinuous 2.3 mile path to Route 49.

A third tornado occurred briefly in Woods Hole after a large waterspout came ashore on Cape Cod before weakening. 

Tornadoes this time of year are unusual and tornadoes in New London County are very unusual. Since 1950 this will be the third on record!

The environment today was much like last week's with strong instability in the lowest 10,000 feet of the atmosphere and adequate low-level wind shear. The atmosphere was not quite as impressive as last week but was enough for tornadoes.

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<![CDATA[Exceptional Tornado Outbreak in New England]]>498370171Tue, 23 Oct 2018 21:22:16 -0400https://media.nbcconnecticut.com/images/180*120/NickHaveran.jpg

Hail in Connecticut, 10 inches of snow on Mount Washington, and at least three tornadoes in southeastern Massachusetts and Rhode Island. Tornadoes weren't in the forecast but the atmosphere was primed for tornadoes. Plentiful low level instability and wind shear produced a swarm of very shallow supercells that starting spinning almost immediately. 

Based on radar, storm surveys, and eyewitness video I'm able to confirm tornado touchdowns in North Providence/Lincoln, RI, Norton, Mass. and Sandwich, Mass. There may have been more. 

To measure instability we use something called CAPE which is an acronym for Convective Available Potential Energy. Values about 2,000 or 3,000 get our attention but today they were almost 10% of that! What was different, however, was that all the instability was in the lowest 10,000 feet of the atmosphere. We can look at just the CAPE in the 0-3km layer and that was between 100 and 200 units which is very impressive. When coupled with strong low level shear we were set for supercells and tornadoes. 

Two of these tornadoes we were able to confirm in real time as lofted tornado debris was detected by Doppler Radar. A Tornado Debris Signature is a confirmation that a tornado occurred as lofted tornado debris has a distinct signature that's different from rain, snow or hail. We noted two large, but brief, tornado debris signatures in Lincoln, RI, and Norton, Mass.

Today's tornado event was extremely unusual. Tornadoes are rare in Rhode Island and even more rare on Cape Cod. Today's tornado in Sandwich was the first tornado in Barnstable County since 1977! A "perfect" combination of low level shear and low level instability wound up producing a widespread severe weather event. 

This event was not forecast at all. It was a big miss. Looking back I see a few signals that showed up last night in some computer guidance but at the time they didn't raise any big red flags to me. By early afternoon, however, it was clear that we had trouble on our hands. A truly unique and unusual day of weather in New England. 

Photo Credit: Nick Haveran / Sandwich, MA
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<![CDATA[Hurricanes and Climate Change]]>497286031Fri, 12 Oct 2018 18:24:55 -0400https://media.nbcconnecticut.com/images/213*120/Hurricanes_and_Climate_Change_1200x675_1343094339925.jpg

Is there a link between hurricanes and climate change? ]]>
<![CDATA[2 More Tornadoes]]>495323801Fri, 05 Oct 2018 21:58:35 -0400https://media.nbcconnecticut.com/images/213*120/norwalk1_1200x675_1338050115689.jpg

Two more tornadoes on Tuesday brings our total to eight tornadoes for the year here in Connecticut making this an exceptionally active year for severe storms. The October 2 event featured a warm front moving north through Connecticut. Tornadoes are frequently found near and along warm fronts and this was no exception. At least 19 tornadoes hit Pennsylvania, New York, and Connecticut. 

One tornado struck Norwalk and New Canaan after producing two tornadoes in Rockland and Westchester Counties in New York. The storm was impressive on radar with very strong rotation detected. An EF-1 tornado was on the ground for nearly four miles from New Canaan into Norwalk. 

Shortly after the Fairfield County tornado a line of thunderstorms in northern Connecticut produced isolated damage in Manchester and a brief EF-0 tornado in Mansfield Center. 

The line of thunderstorms looked impressive on radar but very little wind reached the ground from Litchfield County east into Windham County. For the most part a shallow layer of stable/cooler air near the ground prevented the damaging wind from reaching the surface. These thunderstorms were mainly "elevated" as in they were not rooted in the air adjacent to the ground. 

East of Hartford a mesovortex developed. Think of a spinning complex of thunderstorms (bigger than one spinning thunderstorm like the one in Norwalk and New Canaan). The larger vortex appears to have spawned a smaller vortex - a tornado - over Mansfield Center. This is unusual but not uncommon. Even though the tornado was small it managed to suck a bunch of leaves up into the storm and while only weak rotation was apparent on radar we did detect lofted debris which is a Tornado Debris Signature. 

It's been an active tornado season across Connecticut. While many people are asking "Is this the new normal?" it's important to note that it's been 16 years since our last "significant" tornado (EF-2 or greater) and the last few years have been very quiet severe weather seasons. This year appears to be more of an unlucky abberation than a sign of what's to come in a warming world. 

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<![CDATA[The 1979 Windsor Locks Tornado]]>495105121Wed, 03 Oct 2018 20:57:47 -0400https://media.nbcconnecticut.com/images/176*120/tornado21.jpg

The F4 tornado that hit Windsor, Windsor Locks, and Suffield on October 3, 1979 is arguably the most violent tornado in Connecticut history. The extraordinary and highly unusual circumstances that lead to the Windsor Locks tornado make the tornado not only one of the strongest but also one of most bizarre in New England history.

A strong disturbance in the upper levels of the atmosphere raced northeast toward Connecticut on October 3, 1979. A warm front moved north from Long Island Sound which resulted in a band of extreme low level wind shear over Connecticut. 

The storm that spawned the tornado produced exceptionally heavy rainfall and isolated severe weather from Long Island north into the Hartford area. The storm moved north from New Haven when things turned violent.

According to Riley and Bosart (1987) the radar imagery indicates that the storm may have been a left moving supercell that became tornadic when interacting with the warm front. The observations at Bradley Airport are remarkable. A wind gust of 40 m/s or 90 mph was recorded as the tornado passed just feet from the terminal. 

The weather pattern that lead to this tornado is certainly not a classic setup for a northeast tornado. Riley and Bosart argued in their 1987 paper that the instability was maximized in the Connecticut River Valley with a channeled southerly flow coming up the Valley from the Atlantic Ocean and Long Island Sound that transported warm, moist, and unstable air inland. The combination of instability, strong lift from the approaching upper level disturbance, and extreme wind shear near the warm front draped over BDL was enough to produce a short-lived, isolated, and violent tornado.

The damage was extensive. Flattened subdivisions in Poquonock and flipped planes and helicopters at Bradley Airport. Ted Fujita, the world renowned tornado expert, surveyed the damage and published both the tornado path and the extreme downburst damage that occurred just east of the tornado path. 

The 1979 Windsor Locks tornado remains one of the costliest tornadoes to strike the United States (the damage in three towns amounted to an adjusted 700 million dollars). The fact this tornado occurred in October in a somewhat unusual severe weather setup (a storm moving south to north) makes the 1979 Windsor Locks tornado one of the strangest significant tornadoes in New England.

The 11.3 mile long tornado (officially, though it appears that the tornado was actually on the ground all the way to the Mass Pike!) was 1,400 yards wide at its widest point and is likely the strongest tornado to hit Connecticut in the last 100 years.  Three died in the storm, 500 were injured, and countless others won't forget where they were when one of the state's worst storms moved through.

To read more on the meteorology of the 1979 tornado check out this Monthly Weather Review article

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<![CDATA[October - A Month of Extremes]]>494864351Mon, 01 Oct 2018 22:13:10 -0400https://media.nbcconnecticut.com/images/213*120/Almanac-Custom.jpg

The month of October is a big transition month in Connecticut. It's one of the few months where truly anything can happen weather-wise. Hurricanes, snowstorms, and tornadoes - we've seen it all.

This October is starting off on a warm note. We're expecting above normal temperatures for the first half of the month. The average high temperature on October 1 is 69 degrees. By Halloween the average high is only 58 degrees. Sunset on the first of the month is around 6:30 p.m. and by the end of the month its 5:46 p.m.

Severe thunderstorms are unusual in October but not unheard of. October 3, 1979 produced the most violent tornado in state history when an F-4 ripped through Windsor, Windsor Locks, Suffield, and Agawam. 

Snowstorms are also unusual but can happen. The infamous October Snowstorm in 2011 was arguably the most crippling winter storm since the Blizzard of '78 and the Ice Storm of '73. Perhaps more remarkable was the October 4, 1987 snowstorm that dropped over a foot of snow in Litchfield County. 

Connecticut has also dealt with hurricanes in October. Most recently Hurricane Sandy produced extremely high storm surges on Long Island Sound as it cut west into New Jersey on October 28 and 29, 2012.

Photo Credit: NBC Connecticut]]>
<![CDATA[Ryan Checks in as Storm Picks Up in Wilmington, NC]]>493215951Thu, 13 Sep 2018 23:31:19 -0400https://media.nbcconnecticut.com/images/211*120/RYAN-THUMBNAIL.jpg

Hurricane Florence has weakened to a Category 1 storm with winds of 90 mph as the storm crawls west.

Photo Credit: NBC Connecticut]]>
<![CDATA[Riding Out the Storm]]>493204301Thu, 13 Sep 2018 20:28:01 -0400https://media.nbcconnecticut.com/images/170*120/goes16_ir_06L_201809132318.jpg

We're here in Wilmington, NC as conditions begin to deteriorate. We're in a safe spot out of a flood and storm surge zone and plan on hunkering down until the storm passes.

Hurricane Florence did weaken some today. Winds dropped to 100 mph by 5 p.m. Many people along the coast we spoke with who were on the fence about evacuating decided not to as the storm lost some steam. The worry now, of course, is that Florence may pick up in intensity again later as it remains over extremely warm waters off the coast.

Regardless of how strong the winds are at landfall the threat for serious storm surge flooding and record inland rainfall remains high. We're not quite sure how we're going to get out of Wilmington as the roads in and out are prone to flooding - and the current forecast is for near-record rainfall. 

What has been great to see is people coming together and even coming into the hurricane to help others. The Hurricane Hunter Air Force Reservists are spending time away from their family to fly into the storm. We met a swift water rescue swimmer from Louisiana who drove up and is staying in his car in a parking garage to volunteer! The countless line crews, tree crews, Red Cross and FEMA workers are all doing their best to get the Carolinas through Florence. 

We're here to educate our viewers and keep everyone informed of what's going on here in North Carolina. We'll keep you posted as the storm roars inland.

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<![CDATA[Ryan Flies Along With Hurricane Hunters Tracking Florence]]>493116841Wed, 12 Sep 2018 23:32:26 -0400https://media.nbcconnecticut.com/images/213*120/Ryan_Flies_Along_With_Hurricane_Hunters_Tracking_Florence.jpg

As of 11 p.m. Wednesday night, Hurricane Florence was a Category 2. Chief Meteorologist Ryan Hanrahan rode along with the 53rd Weather Reconnaissance Squadron of the US Air Force Reserve as they flew through the storm and collected valuable data.]]>
<![CDATA[Ryan Hanrahan Flies Into Eye of Florence]]>493096461Wed, 12 Sep 2018 20:31:43 -0400https://media.nbcconnecticut.com/images/214*120/Ryan_Hanrahan_Flies_Into_Eye_of_Florence.jpg

NBC Connecticut First Alert Chief Meteorologist Ryan Hanrahan was on board an Air Force C-130 as it flew through the eye of Hurricane Florence on Wednesday.]]>
<![CDATA[Track Ryan Hanrahan's Hurricane Hunter Flight to Florence]]>492981871Wed, 12 Sep 2018 15:36:36 -0400https://media.nbcconnecticut.com/images/160*131/152311_5day_cone_no_line_and_wind.png

I am on my way to Savannah, Georgia to follow Hurricane Florence into the southeastern U.S. Our first stop will be the 5 a.m. Hurricane Hunter flight with the Air Force Reserve. The 10-hour flight will provide low level reconnaissance of Florence's exact location and intensity. 

The data from the Hurricane Hunters is critical. While we can estimate a storm's intensity from our satellites in space we are unable to get a true measure of a hurricane's strength over the ocean unless we fly a plane through the storm's eye. The Hurricane Hunters have been doing this for decades and they provide some of the most critical pieces of information to meteorologists when a hurricane is approaching land. 

The track of Hurricane Florence remains uncertain. Our afternoon computer guidance shows a number of possibilities and none of them are particularly reassuring. Most of our computer models bring Florence up to the southern tip of North Carolina where the storm stalls and then drifts back southwest toward South Carolina. This stall will allow Florence to drop a tremendous amount of rain inland and pound the coast with nearly a day of destructive winds and storm surge. There is a risk that the storm may stall far enough offshore to limit the wind and surge potential along the coast - at least somewhat - but I wouldn't count on that. 

The threat of damaging wind, rain, and surge now extends well south into South Carolina as well. 

We plan on riding out the storm in Wilmington, NC. We have a safe location and will be providing reports live from the storm starting on Thursday. 

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<![CDATA[Hurricane Florence is Worth Watching]]>492656231Thu, 06 Sep 2018 21:08:49 -0400https://media.nbcconnecticut.com/images/170*120/goes16_ir_06L_201809070020.jpg

Hurricane Florence has my attention. The hurricane is chugging westward and almost all of our available computer guidance shows an awfully ominous scenario about one week from now. 

At first glance, Florence is not in a location that's favorable for a United States landfall. Based solely on climatology (previous hurricanes) the odds of a hurricane in Florence's current location coming close to the east coast are extremely low. This graphic from Bob Hart at Florida State shows how far north and east Florence is compared to where U.S. hurricanes typically track. Less than one percent of storms in this location go on to make landfall in the U.S. (in fact if we dig deeper we can't find any storm in history that has come close). 

What's interesting, however, is that the weather pattern over the North Atlantic is not normal. A highly unusual and anomalous ridge of high pressure is expected to develop from New England through the Canadian Maritimes and North Atlantic next week. This effectively acts as a block for Florence preventing the hurricane from curving out to sea like we typically see storms in this position do. 

While the current position of Florence is highly unusual for a U.S. hurricane threat the developing weather pattern is concerning. It is also highly unusual. Highly anomalous weather patterns can produce highly anomalous results.

So what happens? Our computer models today show a number of different scenarios which is what you'd expect to see for a day seven or day eight hurricane forecast. What's remarkable, however, is how many solutions are awfully close to the east coast. The spaghetti plots below (each "strand of spaghetti" indicates a different computer model solution from either the GFS or European ensemble) show potential tracks of Florence. There are quite a few that show at least some impact from the Carolinas through New England.

Here's what you need to know:

  • At this point some impact from Florence is possible from the Carolinas through New England but what kind of impact is unclear.
  • *IF* we saw something it would likely be Thursday or Friday of next week.
  • There's nothing to worry about right now - but by the weekend that may change. 
  • Most importantly, Florence is a good reminder that you should be prepared for any kind of weather emergency particularly if you live along the shoreline and are in or near an evacuation zone.
  • A direct hit in Connecticut from Hurricane Florence remains exceptionally unlikely. That said, it's something we can't rule out entirely.
  • For now, let me worry about Florence. When it's time we will of course be the first to let you know that you should worry too.

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<![CDATA[Most Humid Summer in Memory]]>492045651Wed, 29 Aug 2018 21:52:57 -0400https://media.nbcconnecticut.com/images/213*120/Sun+and+hot+weather+generic.JPG

If you think this summer has been more humid and more uncomfortable than any you can remember in Connecticut - you would be right. In fact it's been the most humid by a very large margin. 

The numbers, courtesy of Iowa State, are shocking. The hourly dew point reading at Bradley International Airport has been at or above 70 degrees for 623 hours this year! This absolutely destroys the old record of about 400 hours. We're also not done yet! 

We use the dew point to gauge how humid the weather is as dew point is an absolute measure of moisture in the atmosphere. Relative humidity doesn't work because it's relative - for example the relative humidity during a blizzard is generally 100 percent - but you would never describe it as "humid!"

With all the humidity it's not surprising this summer has been both warm and wet. So far, this summer is the eighth wettest on record and the seventh warmest on record. We're not alone. Across the country a large swath has experienced a top 10 warmest summer and the midwest and northeast have been unusually wet.

One reason why the humidity has been so relentless is the remarkably warm water to our south. New Haven Harbor has generally been near or above 80 degrees for the last month. The current water temperature is 83.3 degrees while the average (mean) temperature for this time of year is 75 degrees! 

Is there relief in sight? A bit for Friday, Saturday and Sunday but it doesn't last long. Another surge of uncomfortably hot and humid weather approaches starting Labor Day. Stay cool! 

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<![CDATA[Climate Change Impacts Are Already Here]]>491688121Fri, 24 Aug 2018 21:42:10 -0400https://media.nbcconnecticut.com/images/160*123/screen-shot-2012-11-01-at-1-05-19-pm.png

Nearly $1 billion in property value in Connecticut has vanished due to rising sea levels according to the non profit First Street Foundation.

Across the Tri-State region they found nearly $6.7 billion in lost property value due to sea level rise flooding. In Connecticut they found 14,713 homes lost value due to rising sea levels which amounts to $916 million dollars in lost value.

First Street found Milford as the hardest hit city or town in Connecticut with $127 million in lost property value between 2005 and 2017.

The study controlled for economic trends and was able to, "isolate the impact that increased frequent tidal flooding, caused by sea level rise, has had on home value."

Andrew Freedman, the climate science writer for Axios.com, noted that this is one of a number of new studies with similar results.

This shouldn't come as a susprise. Across the globe sea level has risen approximately 8 inches in the last 100 years due to global warming. Across the northeastern United States the increase has been even more pronounced (due to the fact the land is sinking slowly in this part of the world which magnifies the impact of rising sea level). 

Tidal gauges on Long Island Sound in Bridgeport, New London, and Willets Point (New York City) show the increase in sea level over the past 80 years. The trend is clear that the impact of climate change is already being felt and is likely to become an increasingly bigger problem for towns on Long Island Sound.

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<![CDATA[Where Are The Hurricanes? ]]>491601991Thu, 23 Aug 2018 21:31:05 -0400https://media.nbcconnecticut.com/images/160*120/MOV5-4.14E.GIF

As Hurricane Lane moves toward Hawaii the weather in the tropical Atlantic remains very quiet. The National Weather Service and the experts at Colorado State University are forecasting a quieter than normal hurricane season in our part of the world.

The Atlantic hurricane season peaks on September 10th. In Connecticut, virtually all of our hurricanes have struck in late August, September or October. We have many weeks to go!

Still, this year is expected to be a quiet one for hurricanes and tropical storms and there are two main reasons. The first reason is a persistent area of colder than normal sea surface temperatures between the Caribbean and western Africa. We call this the Main Development Region or MDR. Hurricanes thrive on warm water. Warm ocean water is the fuel the hurricanes need to grow and mature. 

The second, and most important reason for the current dearth of tropical cyclones is the presence of unusually dry air over the Atlantic Ocean. Dry air from the Sahara Desert in Africa has pushed west over the MDR and has essentially prevented much in the way of sustained thunderstorm activity. 

While this year is expected to be a quiet one there is an important cavaet here. It only takes one storm in the wrong place to be catastrophic. One strengthening hurricane near a big city on the Gulf or Atlantic is all it takes to turn a quiet season in terms of numbers into a destructive one in terms of damage. 

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<![CDATA[Tornado Touches Down in Woodstock and Webster, Mass]]>490069311Sat, 04 Aug 2018 17:05:27 -0400https://media.nbcconnecticut.com/images/160*120/DjxeMx4WsAEpOFU.jpg

This seemingly never ending slog of tropical air and rain has produced another round of severe thunderstorms. At least two tornadoes developed from a powerful supercell in Woodstock and Dudley, Mass. 

The damage was thankfully quite minor in Connecticut with only a handful of snapped trees in Windham County. The tornado damage was only evident in two corn fields in the western part of Woodstock where a convergent pattern of downed corn stalks was detected by the National Weather Service.

The thunderstorm that produced the Woodstock tornado went on to produce a substantially stronger tornado in Webster and Douglas, Mass where structural damage was observed in the center of town. 

On radar the strongest rotation was detected over Woodstock. In the upper right frame you can see radial velocity from the Boston National Weather Service radar detecting strong rotation. In the bottom right that rotation shows up as the brighter greens in the town of Woodstock.

This was a setup that was primed for an isolated tornado. The morning weather balloon launch on Long Island detected strong low level wind shear. In fact the Storm Relative Helicity was approaching 200 m2/s2 in the lowest 1km which is an indication of how strong the low level wind shear was. This time of year any warm front or weak low moving over southern New England needs to be watched closely as the water temperatures over the Atlantic and Sound are extremely warm and there's typical ample instability to work with the enhanced wind shear near a front. 

This has been an extremely active severe weather season across New England with multiple rounds of dangerous storms. Hopefully we get a nice break soon!

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<![CDATA[Hot... But How Hot?]]>486632801Tue, 26 Jun 2018 20:51:28 -0400https://media.nbcconnecticut.com/images/160*120/0626euro.gif

A surge of very warm air into New England may bring Connecticut our first heat wave of 2018. While a heat wave appears quite likely what remains uncertain is just how hot it will be. A good way to look at this is this box and whisker plot of the European Ensemble forecast for this weekend. The box represents the most likely solution while the whiskers represent more extreme and less likely scenarios. 

You can see even the middle 50 percent (25th to 75th percentile) is quite large on Sunday. This is not totally surprising given uncertainty into which direction the wind will be blowing from. 

For extreme heat in Connecticut you generally need a westerly wind - this mitigaes the influence of the cooler Long Island Sound and the Atlantic Ocean. Today, most of our computer models showed more of an onshore component to the wind Sunday and Monday which would limit the heat and likely preclude record heat. 

Of course, there is time for this to change! A change in wind direction would result in temperatures approaching 100F. Stay tuned.

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<![CDATA[May 2018 - A Look Back]]>484116341Wed, 30 May 2018 20:46:17 -0400https://media.nbcconnecticut.com/images/213*120/SleepinGiant.jpg

May 15, 2018 will be remembered for some time to come. The four tornadoes and widespread swath of damaging straight-line winds produced one of the most memorable severe weather events in Connecticut in decades.

According to Eversource the damage to their power grid was worse than the damage during Hurricane Sandy with 425 miles of lines needing to be replaced. Power outages lasted for over a week in some of the hardest hit towns. To the best of my knowledge this was the largest utility outages from thunderstorms on record. 

One thing that has been interesting about this month was just how warm it was. I would guess if you asked most people in Connecticut if they thought the month was a chilly one the vast majority would say it was! In reality as of May 30 this May tied for the 4th warmest on record!!

Don't get used to it, however. At least in the short to medium term there is some ugly weather that appears to be lurking nearby. Both the GFS and European models show a deep and persistent trough of low pressure to the south of us over the weekend and into the middle of next week.

While the details of just how cold and just how wet remain to be worked out it's fair to say the upcoming pattern is anything but pretty. June is going to start on a very unsettled note.

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<![CDATA[May 15, 2018 - Northwest Hills Hail and Tornadoes]]>483273991Mon, 21 May 2018 21:26:10 -0400https://media.nbcconnecticut.com/images/160*120/DdvR_gcUwAE78QD11.jpg

An exceptional severe weather event produced 4 tornadoes, tennis ball size hail, and a swath of damaging wind for nearly 40 miles throughout Fairfield and New Haven Counties. The amount of damage over such a widespread area makes this one of the biggest severe weather events in Connecticut since the July 1989 tornado outbreak.

The first storm of the day was a powerful supercell that entered northwestern Connecticut after 3 p.m. It produced two tornadoes, damaging straight-line winds, and hail to the size of tennis balls in Hartland and Granby. this was a remarkably powerful storm.

The storm produced a tornado in Ulster County, New York and baseball size hail in Columbia County, New York. By the time the storm entered Connecticut it was very close to producing a tornado in Salisbury with an area of tight rotation in the far Northwest Corner. Hen egg size hail fell in Canaan as the storm moved east along Route 44.

A vertical radar cross section over Hartland as tennis ball hail was being produced. In the foreground you can see the hook echo that was producing a tornado over the Barkhamsted Reservoir.

The storm also produced a brief tornado just north of downtown Winsted.

The largest hail fell over a very rural part of the state - and still the damage was quite severe. Dented cars, busted windshields, and destroyed siding. If this storm occurred over the I-91 or I-95 corridor the losses would have been staggering.

As the storm entered a more stable airmass over the Connecticut River Valley it weakened. A 47 knot wind gust was recorded at Bradley and that was about the end of the storm as it moved east and fell apart.

Tennis ball size hail (2.5" diameter) is the largest hail to fall in Connecticut since the June 1995 supercell that dropped baseball size hail in Ellington and Lyme.

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<![CDATA[May 15, 2018 - Southbury to Hamden Tornado]]>483123751Sat, 19 May 2018 17:08:53 -0400https://media.nbcconnecticut.com/images/160*120/oxford051918.jpg

At least two tornadoes struck New Haven County the afternoon of the 15th. The first tornado touched down near Bullet Hill Road in Southbury and continued into Oxford. A second tornado developed near the center of Beacon Falls and continued into the hills of Hamden to the west of Route 10.

The two tornadoes were within a path of destructive straight line winds. There could have been several more spin ups that we'll never know about. Some of the areas hardest hit like Bullet Hill Road in Southbury, Hogs Back Road in Oxford, and Fairwood Road in Bethany had clear tornado damage with countless snapped trees. Elsewhere, a large area of damaging wind produced exceptional damage.

On radar this storm had a clear evolution from a supercell to a bow echo - in other words a storm that transitioned from one producing a tornado to one producing straight-line winds. Trying to distinguish between the two is challenging to say the least.

The destructive winds in Newtown moved over the Housatonic River in Southbury and quickly spun up a tornado. It's possible that the winds near the ground were locally backed (out of the southeast up the river valley) which lead to a very localized increase in shear. This could have been enough to spawn the tornado just east of the river near Bullet Hill Road in Southbury.

After the tornado touched down around 4:54 p.m. we detected a tornado debris on radar at 4:58 p.m. This was a first in the Connecticut TV market as we were able to see lofted debris on Doppler Radar live on the air moments after the tornado touched down in Southbury. There was a clear debris signature just south of Southford.

Dual polarization radar allows us to determine what kind of targets the radar beam is hitting. Whether it be big rain drops, small rain drops, big fluffy snowflakes, tiny snowflakes, hail, smoke particles, bugs or tornado debris - each target has a unique signature. In this case pieces of leaves and twigs were being lofted by the tornado into the storm's updraft. This gave us clear evidence so we could confirm a tornado had touched down.

The first tornado over Soutbury and Oxford lifted and a second tornado touched down over Beacon Falls. There were several areas of rotation and it's possible more than one tornado touched down. The tornado reached its peak intensity over Bethany around Fairwood Road and in the western hills of Hamden. 

A second tornado debris signature occurred over Bethany as the tornado strengthened. There was a large area of powerful straight-line wind damage in Bethany but a somewhat narrow tornado path on the south side of Route 42 and over Fairwood Road. The damage on Fairwood Road was exceptional. The peak intensity of this tornado was an EF-1 or 110 mph. 

Beyond Bethany the storm's rotation began to weaken and the tornado lifted quickly in Hamden. 

When the tornado lifted a powerful swath of damaging winds continued from Sleeping Giant State Park to Wharton Brook State Park in North Haven and then into Wallingford and Northford. As the storm's rotation weakened the storm became "outflow dominant" with the Rear Flank Downdraft of the storm rushing east and producing winds of up to 100 mph. 

On radar the somewhat "tight" rotation over Bethany became more broad over Hamden. What was interesting is that the debris lofted into the clouds from the tornado in Bethany fell out of the storm over Hamden. We could detect the tornado debris falling out of the storm as it crossed Route 10 and headed into North Haven. 

Hamden is certainly no stranger to tornadoes. The damage from the May 15, 2018 storm pales in comparison to what was done during the July 10, 1989 F4 tornado that swept houses in Newhallville clean off their foundation. Still, the damage from this storm across a large chunk of New Haven County is some of the worst the state has seen from a thunderstorm in quite some time. 

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<![CDATA[May 15, 2018 - Fairfield County Wind Damage]]>482988821Thu, 17 May 2018 20:55:09 -0400https://media.nbcconnecticut.com/images/160*120/brookfield1.jpg

An exceptional severe weather event produced 4 tornadoes, tennis ball size hail, and a swath of damaging wind for nearly 40 miles throughout Fairfield and New Haven Counties. The amount of damage over such a widespread area makes this one of the biggest severe weather events since the July 1989 tornado outbreak.

A substantial area of wind damage occurred from the New York border to Southbury near the Housatonic River. New Fairfield and Brookfield were particularly hard hit along with portions of Newtown, Danbury, Sherman, New Milford, and Bridgewater.

The signal on radar was frightening and clear as day. An embedded supercell on a line of thunderstorms was producing exceptional wind. On the Long Island radar winds of nearly 115 mph were measured less than 3700 feet above the ground blowing toward the radar site. This is by far the most impressive wind signature I've seen in Connecticut. Nothing has come close.

The winds were estimated by the National Weather Service to be between 100 and 110 m.p.h. in this area. That matched up very closely to what we were seeing on radar.

As the storm moved toward the Housatonic River we saw more evidence of rotation and a tornado developed in Southbury.

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<![CDATA[Powerful Thunderstorms on Tuesday]]>482609691Mon, 14 May 2018 21:12:14 -0400https://media.nbcconnecticut.com/images/213*120/Model+RPM4+Precip+Cloud+CT+no+banner0514.png

An unusual combination of very strong wind shear and strong instability may lead to a powerful round of thunderstorms in the afternoon. Something called an Elevated Mixed Layer (or EML) is expected to be overhead Tuesday afternoon and that tends to raise the stakes for severe weather - including large hail, damaging winds, and even tornadoes. Most of our major severe weather events have occurred with an EML present.

Steep mid-level lapse rates on the order of 8C/km will setup overhead Tuesday afternoon. This means the temperature is dropping 8 degrees celsius every kilometer you go up in the atmosphere. This is a rapid decrease! We look for this signal about 10,000 to 20,000 feet above our heads. This can lead to some wicked instability and can help air parcels in thunderstorms accelerate rapidly as they hit the pocket of greatest instability above our heads.

Additionally, we're expecting about 50 knots of deep layer wind shear. Wind shear is critical for thunderstorms to organize. Strong shear can result in well organized lines of storms that can effectively transport damaging winds to the ground. Strong shear is also critical for storms to begin rotating and can create supercells which increases the storm's updraft and also the potential for large hail. 

While some of our biggest severe weather days have featured an EML (think July, 1989 tornado outbreak, 1995 northeast derecho, etc.) it won't be hot or moist enough to result in weather that severe. Still, there is certainly an elevated risk for big hail, damaging winds, and even tornadoes. This is an unusual combination of factors we have so we need to be ready for unusually powerful storms.

The storms will move into the state after 2 p.m. in the Northwest Hills and continue southeast from there. Normally, storms weaken quickly this time of year near the coast but given the steep lapse rates and EML these storms may have more longevity that unusual. 

While there is plenty of wind shear there isn't much directional shear - the wind speed increases rapidly with height but it doesn't change direction with height. Given that and the fact storms will likely organize in a line and not remain discrete any tornado activity should be isolated - though it is possible. 

We'll keep you posted tomorrow as the storm's approach Connecticut. While severe storms are a good bet - just how strong they are will come down to very small scale features that are a challenge to identify too far ahead of time. 

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<![CDATA[Severe Weather Threat]]>482497551Sun, 13 May 2018 19:29:39 -0400https://media.nbcconnecticut.com/images/160*120/NAMNSTNE_prec_radar_051.png

To get severe thunderstorms you generally need two ingredients: instability and wind shear. The magnitude of both roughly correlates to the possible intensity of thunderstorms. 

By Tuesday afternoon a cold front will sink to the south and ahead of it will be a favorable juxtaposition of shear and instability for severe storms. These graphs show instability and shear forecasts for Bradley Airport - and you can see both spike significantly in the afternoon on Tuesday.

48 hours out there can be a lot of changes. This isn't a slam dunk as forecast thunderstorm development and severity is a challenge! There are a few things I'll be watching over the next day or so. 

  • Where does the front set up? Will the front be pushed farther south than currently expected. This could put us on the cooler and stable side of the boundary.
  • Will there be morning storms or rain that prevent enough solar insolation and thereby limit instability?
  • How much instability will there be? The key to this is getting enough low level moisture (high humidity near the ground) coupled with a rapid temperature drop with height above our heads. 
Tuesday is worth watching with the potential for strong thunderstorms - patricularly west of I-91. We'll keep you posted!

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<![CDATA[From Winter to Summer]]>481309721Mon, 30 Apr 2018 20:18:05 -0400https://media.nbcconnecticut.com/images/160*120/gfs_t2maf_slp_ma_14.png

Around 10 a.m. a burst of snow produced some minor slushy accumulation in the town of Norfolk, CT. The town's nickname "Ice Box of Connecticut" lived up to the billing today! Of course, around 1300 feet above sea level snow this time of year isn't terribly unusual. Snow fell in May in the town of Norfolk last year, in 2016, 2010, and 2005. 

The snowy end to April is fitting. This April will likely be the coldest since 1956 in the Hartford area which shows just how remarkably chilly the month was. Not only was it cold it was also wet with 7.76" of rain in Prospect and 6.58" here in the station. 

Even though April ended as a dud May is going to begin as a scorcher. I'm forecasting 86 degrees for Wednesday and Thursday which is WAY above average. The warmer temperatures will be accompanied by some humidity and I wouldn't be surprised if some people flipped on the a/c by Thursday afternoon!

One thing we will have to watch is the potential for a strong thunderstorm Thursday evening. Warm air, increasing levels of humidity, and increasing wind shear are ingredients that could support severe storms.

Severe weather is unusual in early May but it's not unheard of. We'll be watching it as we get closer. 

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<![CDATA[The Nor'Easter That Wasn't]]>477989503Mon, 26 Mar 2018 21:34:11 -0400https://media.nbcconnecticut.com/images/216*120/wx1032618.PNG

A forecast of 6"-12" 48 hours before the storm hit. Actual snowfall at Bradley Airport? 0.1 inches. Oof.

So what the heck happened?  The biggest problem with the forecast was that the storm wound up about 100 miles south of where I expected it to. Very dry air in the low levels of the atmosphere wound up overhead here in Connecticut resulting in little snowfall. On Long Island, however, nearly 20" of snow was reported in some towns!

The day prior to the storm it was clear that this one would be a challenge to predict. I tried to convey that as best as I could on Twitter, Facebook and also on our the broadcast side. I was about as uncertain as I can recall being recently about a snow forecast.

What was a challenge for us was that some of our modeling continued to show a big hit. The European model first cut back showing a dry air issue and a track to the south but virtually every other piece of guidance did not Tuesday afternoon. In fact, some of our high resolution modeling was predicting 20" of snow near New Haven the day before the storm - with an extremely sharp gradient to the north.

As it turns out the wacky 20" forecast was only off by about 25 or 30 miles - it fell over Long Island! Consistently our forecast was less than the National Weather Service which as late as midday Tuesday as predicting over a foot of snow for all of Connecticut. On Wednesday afternoon they were predicting up to a foot of snow for the shoreline. To people who say our forecasts were "hyped up" I can assure you they were not. They were wrong. They were too high. But they weren't hyped - in fact we were forecasting about 50% of what the National Weather Service was predicting.

I'm not sure what I would have done differently with this storm and that's what's most frustrating after the fact. I could see reasonable arguments for more or less snow with the modeled setup. Even as late as Wednesday our models were having fits trying to figure out how far north the snow would get. Some storms are just difficult to model. They're extremely sensitive to small changes and those sensitivities grow into huge errors in time.

One thing that many people - including an article in the Washington Post pointed to - was the high March sun angle as the culprit for the busted storm. Nonsense! In the parts of Connecticut that had snow the ratio of snow to liquid water was around or even better than 10:1! The snow didn't have much of a problem sticking when it was falling at a moderate rate. New Haven only picked up 0.11" of precipitation where the model consensus prior to the storm was over 1". This was an issue of just not getting any precipitation - not the sun angle. With a cold, dry air source to the north this was never going to be an issue with the strong March sun - if anything the cold and dry air proved too much here locally and kept the precipitation south. 

A lot of people reached out and asked us why the forecast was so wrong. I hope this helps answer that question some. One thing I think is very important to point out is that even though this forecast was a bust weather forecasting is getting very, very good. Storm misses like this one happened with great regularity 15 years ago. Now they're fairly unusual.

Our computer models are now able to track hurricanes and blizzards 7, 8, or 9 days out. Irene and Sandy were on our radar almost a week out! Hurricane Bob (1991) wasn't really on anyone's radar until Saturday morning. It hit midday Monday. Imagine a hurricane appearing just 48 hours out now? I can't even fathom a scenario where that would happen locally.

The July 1989 tornado outbreak came as a surprise to most and the monster supercells were poorly warned. We forecast the potential for tornadoes 3 or 4 days before the 2011 Springfield tornado. Our Doppler Radar technology allows us to give warnings before a tornado is produced - and we can even see radar signatures for lofted debris after a tornado has touched down. In some respects, we're victims of our own success. During the storm a few weeks ago we were able to see snowflakes change their orientation in the clouds due to increased electrical fields and had a 5-10 minute heads up that thundersnow was likely. As forecasts have gotten better the expectations from the public have increased! 

The job of a meteorologist has changed. People who claim we can "beat the models" are fooling themselves. We can't. We can do a better job expressing uncertainty. You can't get that on an app. Which forecasts are we confident in and which forecasts are we not confident in? This one was certainly the latter - and we knew that! People who watched our forecast the old fashioned way on TV (and many people did based on the ratings!) knew that this forecast was unusually challenging, we didn't expect much accumulation during the day, and that they should expect big changes. People who used just an app likely didn't know any of that. There is huge value in TV weather as we can add context, understanding, and local perspective you won't find on your phone. 

Beyond expressing uncertainty in a forecast human meteorologists still have a big role to play in the process. Accounting for model biases, knowing which models to use and when, recognizing that uncertainty, converting raw model guidance into real world impacts, communicating complex weather events to the public are all critical jobs that still need to be done. 

We don't get them all right but we try like hell every single storm. Ditch the app on your phone that shows random numbers and icons and make the time to catch the weather on local TV before work, after work, or before bed. You'll be much better informed.

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<![CDATA[March 13, 2018 Snow Storm]]>476889533Wed, 14 Mar 2018 21:30:44 -0400https://media.nbcconnecticut.com/images/213*120/DYNQrOiXkAITzTx.jpg

Tuesday's snowstorm was a challenging one for me. The storm tracked hundreds of miles southeast of Connecticut - a track that would ordinarily be a complete miss or just a glancing blow for us. The end result, however, was up to 26.0" of snow in the town of Scotland!

The day before the storm we saw the ingredients coming together for a more substantial system. Even though the storm would pass well out to sea the best "lift" in the atmosphere was going to be displaced far to the north and west of the storm's center. Two bands of stronger lift were well modeled by all of our computer models - one over eastern Massachusetts and another closer to Connecticut. The question was how far west would these bands get? How much sinking air in between bands would result in less snow? How slowly would these bands move? Beyond that another question was what type of snow flakes would we get and how fluffy would the snow be? 10" of snow to 1" of liquid water or 20" of snow to 1" of liquid water? As it turned out we saw both!

Strong low level convergence (effectively air that piles onto itself and has nowhere to go but up) was going to be the big snow producer in New England. Not surprisingly, snowfall totals of up to 31" occured outside of Boston in this big band that stretched from coastal Maine to southeastern Connecticut. Knowing that this would setup was an easy call - but there was some uncertainty as to whether Connecticut would get in on the fun. Locally, the band produced snowfall rates of up to 5" per hour and snowfall totals of over 20" in parts of New London and Windham Counties as it did wobble far enough west to smack us. 

In the areas where snowfall rates were less temperatures above 32 degrees and the strong March sun angle resulted in a very low impact storm. Bradley Airport managed 6.9 inches of snow but you wouldn't know it by the roads around Windsor Locks! Same storm in Bridgeport where 5.5" of snow fell but roads were fine. In eastern Connecticut the fluffy 2 feet of snow that fell in some towns compacted rapdily and by mid morning today only about a foot of snow remained.

But what about that second band farther west?

The mechanism for the snow band over western and central Connecticut (it produced 10" of snow in some of the Litchfield Hills and parts of Fairfield County) is something known as frontogenesis. About 10,000 feet above our heads the wind resulted in "deformation". The wind acted to stretch the atmosphere parallell with the temperature gradient which strengthened the temperature gradient between warm air and cold air. Think of it this way, as the atmosphere was being stretched the distance between relatively warm adn relatively cold air was becoming less and less. This is frontogenesis or the stregthening of a font! This results in a thermally direct circulation with warm air rising and cold air sinking on either side of the circulation. The rising side gets a band of very heavy snow (only about 10 miles wide in the case) while the sinking side gets no snow at all. 

As always these storms are challenging to predict and figuring out just how far west these snow bands would get was a bear. Take for instance Clinton and Waterford. About 20 miles made the difference between 3.5" and 18.0" of snow. We are very good at predicting whether or not a storm will hit us days ahead of time (though in the 24 hours before the storm a jump in storm track by about 75 miles was critical for us).

The predictability of very small scale circulations that result in narrow bands of heavy snow have an exceptionally short predictability horizon. This gives plenty of fodder for unhappy viewers on social media who have come up with dozens of different ways to call me an idiot for a bad forecast for their backyard (I admire the creativity of some!) but it also provides ample opportunity for improving and learning about these really fascinating features.

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<![CDATA[Wednesday's Nor'Easter]]>476325433Fri, 09 Mar 2018 01:07:02 -0400https://media.nbcconnecticut.com/images/160*120/DXxtoexXcAE2DHY.jpg

160,000 utility customers were in the dark after Wednesday's vicious nor'easter dropped up to two feet of snow in some towns in western Connecticut. The heavy, wet nature of the snow did the most damage with trees snapping and power lines coming down all over southern and eastern Connecticut. The storm's snowfall distribution was a typical one for a nor'easter with two bands of very heavy snow.

One band was located far to the west from New Jersey through Danbury and north into the Berkshires and southern Green Mountains (where nearly 40" of snow fell in one town). A second maxima was located farther east from Portland, Maine south through central Connecticut and into Long Island.

The band to the west was primarily driven by what we call "frontogenesis". Effectively a front was forming high in the atmosphere (nearly 15,000 feet above our heads) and a localized area of intense lift resulted in a heavy band of snowfall that effectively rotted in place for hours and hours. In this band snowfall crystals grew with great efficiency and the snow that did accumulate was quite fluffy! Warren picked up 25.5" of snow in 24 hours with a liquid equivalent of 1.56" making this a 16:1 ratio of snow:liquid. To put that in perspective the 10.8" of snow in West Hartford I measured had a ratio of 9:1. 

We can visualize this by looking at this cross section produced by SUNY Albany grad student Tomer Burg showing the band of lift in the atmosphere (look where the arrows point upward) starting low in the atmosphere in eastern Connecticut and winding up much higher up over western Connecticut and New York. The band over western Connecticut was the most persistent and the snowflakes that were growing (rapidly, and efficiently) were dendrites that piled up quickly. 

Another interesting thing you can see in both the cross section and the snowfall analysis is the local minima in snowfall between the two bands. A combination of sinking air and warmer air in the valley lead to relatively lighter snowfall amounts in the northern Connecticut River valley (8.7" at Bradley Airport). 

Believe it or not we can see the rapidly growing dendrites on dual polarization radar. The big dendrites that formed in the western band (that accumulated very readily) fall flat as they float to the ground. When the horizontal radar beam hits the snow flakes (that are oriented horizontally) and encounters a very large number of flakes the radar's beam slows down. The horizontal beam is now slower than the vertical radar beam and this results in an increase in Specific Differential Phase (known as KDP). We can see these large number of dendrites clearly on radar with a spike in KDP about 10,000 feet above the ground. The signature appeared periodically across the state but lasted for hours over the hills indicating snow flakes were growing rapidly and with great efficiency in the western band. 

Radar also picked up something we typically see in our strongest nor'easters. Thunder and lightning was common across the state yesterday evening with great displays of vivid lighting and booming thunder. As the electrical field grows in clouds the ice crystals tend to align with the electric field. As the radar beams (horizontal and vertical in dual pol radar) encounter these canted ice crystals the forward propagating radar beam begins to lose its orthogonal polarity - for instance the horizontal radar beam becomes more vertical. This produces a radar artifact down radial and you see streaks of either high or low ZDR known as depolarization streaks. This signature frequently precedes thundersnow as the electric field of the clouds eventually discharges in a lightning strike. 

We had been forecasting thundersnow for 2 days as there was a very robust signature on our computer modeling for an area of instability in the atmosphere. You can see in this weather balloon launch on Long Island what we call a MAUL or Moist Absolutely Unstable Layer which is the instability necessary to develop a thunderstorm. You can identify this feature by looking for an area where the temperature rapidly decreases with height (in this case a sudden jerk to the left when reading the diagram from bottom to top). In this sounding you can see it near 700mb where there is a sharp decrease in temperature which creates an absolutely unstable layer and favored thunderstorm development. 

Of course, temperatures near the ground played a big role in how much snow accumulated. In the valley locations snow was initially slow to accumulate and in the hills where it was colder the snow accumulated more rapidly. There was certainly an increase in snow totals on hill tops than in valleys. Take New Milford, for instance, where 10" of snow fell downtown but 18" fell in the hills of town!

Where temperatures were warmest - and where nearly a foot of snow fell - in towns like Guilford, Madison, Branford, Killingworth, Essex, and Deep River the tree damage was extensive. The outage map from Eversource illustrates this quite well. With 2 feet of snow in Warren there were few issues (snow was dry and fluffy) but the paste on the shoreline took down trees and power lines all over the place. 

Photo Credit: Eversource
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<![CDATA[Powerful Nor'Easter; Extremely Challenging Forecast]]>475480233Thu, 01 Mar 2018 09:02:16 -0400https://media.nbcconnecticut.com/images/213*120/Morning_Forecast_for_March_1_1200x675_1174048323705.jpg

Nothing about this forecast is easy. The nor'easter that forms off the coast is a classic. It has just about all the ingredients needed for a beast of a storm with one exception. That missing ingredient is - cold air! 

Temperatures Thursday will climb through the 50s across the state. To the north over Canada there's no good source of cold air. What would ordinarily be an "easy" forecast of 1-2 feet of snow is suddenly quite challenging. How quickly will temperatures cool and how quickly will the rain change to snow. 

An upper level low will close off just south of New England on Friday. As it does the storm will essentially stall, Do a small loop-de-loop, and then push offshore. It's that "loop" that makes this storm so intriguing and is a hallmark of most of our biggies. The intensity of the storm as it matures just off the coast is also remarkable. Winds about a mile off the ground are progged to approach 100 mph over parts of southern New England.

So, the main pieces are on the table. Heavy rain and strong winds (gusting up to 60 mph) are quite likely. The storm reaches its peak intensity around midday Friday and we will be on the northwest side of both the surface and mid level lows (think of 0ft-10,000ft above our heads) and this is critical. As air rises quickly the atmosphere cools to the northwest of these lows. Additionally heavy melting snowflakes will cool the column as energy is expended to melt the snow into a rain drop. Both processes will be in play on Friday and it appears we will cool enough for a thump of snow - especially in the hills.

I do know that our snow forecast is higher than any of the other local outlets by a good amount and is substantially higher than the National Weather Service. I could certainly be wrong here! But, this kind of storm looks to me like it will be so intense even in a borderline situation we will likely flip to snow. In the hills a few hundred feet of elevation will go a long way and there may be substantial snowfall differences between hills and valleys. The CIPS analog guidance has the April fools day blizzard of 1997 as its number one analog for this storm which is certainly saying something!

For our snow forecast we discounted the GFS low level temperatures (it is frequently way too warm in these setups and is basically unusable) and we've blended the thermal profiles from the NAM and European models. Additionally, our snow forecast matches closely with the European ensembles - below is the probability of 6"+ of snowfall and you can see greater than 50% odds where we have our 6"+ contour in the Northwest Hills. 

Other issues we will have to deal with are damaging winds (especially with heavy, wet snow accumulating on trees and power lines) and coastal flooding. We are quite confident in 40-60 mph wind gusts across the state. As for coastal flooding it appears we may get lucky with a more northerly component to the wind. This essentially directs the wave action away from the shoreline and limits issues. I do see anticipate widespread minor to locally moderate coastal flooding given the combination of storm surge and astronomically high tide.

The threat for coastal flooding - and potentially major coastal flooding - is much higher around Boston where the wind will be more onshore. 

Stay tuned for updates - I'm sure there will be many!

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<![CDATA[Friday Nor'Easter]]>475105783Sun, 25 Feb 2018 22:56:31 -0400https://media.nbcconnecticut.com/images/160*123/ecmwf_apcp_f114_ne.png

A powerful coastal storm is expected to develop off southern New England Thursday and Friday and will deliver a number of weather problems to Connecticut. We have been talking about this storm potential for days as a giant atmospheric block over Greenland sets the stage for a sizable nor'easter.

One thing to note about this storm is that it doesn't not have a tremendous amount of cold air to work with. While heavy snow is a possibility for many valley and shoreline locations rain seems favored as of now (of course, given that this is 4 days out, this could change).

Here are a few of the possible impacts.

Heavy Rain

Our computer models all bring a tremendous amount of moisture into Connecticut off the Atlantic Ocean. Most of our computer models are showing anywhere between 1"-3" of precipitation. In a setup like this locally higher totals would be possible.

Strong Winds

The storm is expected to rapidly deepen below 980mb. The difference between high pressure to the north and low pressure to our south will create a strong pressure gradient. Damaging winds are possible.

Coastal Flooding

A strong easterly flow coupled with high astronomical tides may lead to coastal flooding in Long Island Sound. The full moon on Friday morning will lead to the highest tides of the month. Storm surge and wave action on top of this makes us concerned about the Friday morning high tide.

Heavy Snow

This storm has the look of a late fall or early spring nor'easter. There's just not a lot of cold air nearby! This could be a storm with wild differences in snow totals between the valley floors (where it's mainly rain) and hilltops (where more snow is possible). It's obviously way too early for amounts or specifics but a word of caution here - this storm will likely be very intense and moisture laden meaning places that stay all or mainly snow could get dumped on! 

Bottom Line

We are confident in a strong coastal storm impacting Connecticut Thursday night and Friday. Strong wind, coastal flooding, heavy rain, and heavy snow are all possible across the state. How significant each hazard will be remains to be seen and will be determined by the storm's exact track, evolution, and strength. Storm track errors fo 100-200 miles are common in the 4 day time range and that can make a HUGE difference. 

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<![CDATA[Record Warmth and Climate Change]]>474780403Wed, 21 Feb 2018 22:32:39 -0400https://media.nbcconnecticut.com/images/213*120/rh2_1200x675_1166996035997.jpg

Today's high at Bradley Internation Airport was an astounding 77 degrees.

The record hightemperature for the day in Hartford fell by 14 degrees. The all-time February high temperature record fell by 4 degrees. Of the 6 times the Hartford area has reached 70F in February - 3 of them have occured in the last year. This was the warmest temperature recorded in the Hartford area during meteorological winter. By any metric the warmth today was remarkable. 

From a meteorological perspective what we saw was unprecedented. One of the most common things we display on weather maps is something called geopotential height. Geopotential height (GPH) is the height above sea level a certain pressure level is found in the atmosphere. The higher the GPH the warmer the atmosphere below that level as warm air is less dense than cold air. Warmer air effectively takes up more space. Using GPH is useful since it is all relative to sea level - otherwise the height of a pressure level above the ground would be more closely related to elevation of the ground than the atmosphere's warmth.

During last night's weather balloon launch on Long Island the height of the 500mb level was an absolutely astounding 5880 meters. That would be a "warm" value for the dead of summer. Seeing that in the winter is simply unheard of. It just doesn't happen. We broke the previous record by nearly 100 meters which is a HUGE margin. 

The question becomes was today's record shattering warmth caused by climate change? Having 3 of the 6 warmest February days occur in the last year is pretty odd! The answer, of course, is complex.

Extreme heat (compared to normal) is becoming more common as the climate warms. We are seeing this year after year in Connecticut. Winters are warming and they're also shrinking duration. Since 1970 the typical "frost-free" season has grown by weeks with the first frost coming later and the last freeze coming earlier. Winters have warmed by nearly 4F.

Of course, day-to-day weather is full of extremes and ups and downs. Was it possible for a day to be this warm 500 years ago? Sure. Are days like this more likely now? Absolutely. Will they be more likely in future winters? Yes. We're effectively loading the dice toward warmer weather patterns and more extreme heat. We see this as record high temperatures already dramatically outpace record cold temperatures. 

There's a lot we don't know about how a warming world will specifically impact Connecticut. The atmosphere doesn't act linearly and feedback loops with a warmer ocean to our south and record heat over the Arctic to the north are capable of doing all sorts of wonky things. What we do know is that winters are getting warmer and extreme warmth is becoming something we should expect to see more and more. 

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<![CDATA[Record Warmth Approaching]]>474522963Mon, 19 Feb 2018 21:07:04 -0400https://media.nbcconnecticut.com/images/213*120/Model+iCAST+Temp+CT20215.png

Remarkably warm weather will settle across New England Tuesday and Wednesday with temperatures soaring into the 70s in some locations. In the Hartford area we're forecasting 72F on Tuesday! This kind of warmth is extraordinary for February with 70F temperatures having been achieved only 5 times since 1905.

  • 2/24/1985 - 73F
  • 2/24/2017 - 72F
  • 2-16/1954 - 72F
  • 2/25/2017 - 70F
  • 2/25/1976 - 70F
What's even more remarkable is that two of those five 70F days occured just last year. This year, A ridge of high pressure (exceeding 594dm - something that's typical in June and not February) will develop like a summer "Bermuda High." A ridge of this strength is outside of climatology. What I mean by that is that what is being modeled for Tuesday and Wednesday has not been observed in at least the last 37 years.

Something doesn't seem right here.

As the earth warms extreme periods of warmth during all seasons will become more frequent. According to the International Panel on Climate Change (IPCC) report it is very likely that the number of cold days and nights has decreased and the number of warm days and nights has increased. Human influence is by far the largest driver of climate change.

As the earth continues to warm we're essentially loading the dice. Extreme warmth in winter, or any time of year for that matter, is more likely. Sure it can still get cold and we can still get a lot of snow (in fact, no decrease in annual snowfall has been observed even as temperatures warm locally) but extreme warmth year after year is becoming more common.

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<![CDATA[Weekend Snow Risk]]>474114783Wed, 14 Feb 2018 21:41:15 -0400https://media.nbcconnecticut.com/images/160*120/snow2142018.png

Over the last 24 hours there isn't much more clarity about our weekend snow threat. We know the pieces are there for accumulating snow but will they come together? Part of the reason for the uncertainty is that the upper level disturbance we're watching isn't even in North America! 

Once the "shortwave" as we call it moves through Alaska into Canada our computer models should have a better handle on what evolves this weekend.

For now there's not a whole lot we can say other than there's the potential for accumulating snow this weekend. If we get snow it's likely to be Saturday night. It's a quick hitter - it's flying along and should be out of here around daybreak Sunday. As for amounts the graphic at the top of this image from the European Ensembles seems reasonable - about a 50% chance of 3" of snow across the state.

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<![CDATA[Big Warmth Possible]]>473859513Mon, 12 Feb 2018 21:24:47 -0400https://media.nbcconnecticut.com/images/160*120/eps_t850a_conus_37.png

Weather Twitter lit up over the last 24 hours with some absurdly warm air expected to overspread the northeastern United States early next week. There are a few ways to look at this. For one, check out the 10 day European model high/low forecast for Bradley Airport. That is record breaking warmth for next week - a truly impressive display for February.

Put another way check out the 850mb temperature departures posted at the top of this article. Those are anomalies of +10 to +15C a few thousand feet above our heads. Given a favorable wind direction 70F would certainly be a possibility with these kinds of anomalies.

It shouldn't be a surprise that we're looking at a big warm up. This is a classic La Nina setup with a powerful southeastern ridge flexing it's muscle. Colder temperatures with a trough out west and warmer temperatures with a ridge out east. The 6-10 day 500mb anomalies show this quite well with a very amplified jet stream pattern.

Beyond day 10, however, there are some caution flags that our computer models are throwing up. The biggest is the large and impressive -NAO that develops over Greenland as a powerful Rex Block sets up over the North Atlantic. The -NAO may modulate the storm track so that what would have been warm cutters manage to slide nearby or underneath New England. This will have to be watched.

The bottom line is that above normal - and possibly record - wamth is possible in the day 7-10 range. Beyond that, however, I wouldn't write off winter yet! 

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<![CDATA[Remembering the Blizzard of 1978]]>472838753Tue, 06 Feb 2018 07:05:07 -0400https://media.nbcconnecticut.com/images/182*120/AP_7802080130.jpg

Forty years ago one of the biggest blizzards to strike Connecticut dropped nearly 2 feet of snow along with wind gusts of near hurricane force. At Bradley Airport only 16.9 inches of snow was recorded but many towns measured 24 inches including Thompson, Norfolk, Coventry and Hamden. 

Wind gusts of 60 knots (about 70 mph) in Groton whipped the snow into monstrous drifts. The sudden onset of the storm stranded thousands of people all across the state. The storm was forecast quite well. This 48-hour forecast from the Limited Fine Mesh model (LFM) is remarkable for its accuracy considering how primitive computer modeling was. 

The Hartford Weather Service Office in Hartford transmitted several messages from Governor Ella Grasso during the storm. 

The storm is remarkable for the amount of disruption it caused. Many people didn't believe the weather forecast after a large snowstorm forecast bust two weeks prior. With most of the snow coming during a short period of time in the afternoon people were stuck on roads across the state. Along the coast significant coastal flooding caused severe flooding in many towns. 

The drifts of snow from the storm are what most people remember - along with the highways that turned into parking lots as cars were quickly buried by the snow. There have certainly been storms that have produced more snow (the 2013 blizzard, for example) but the 1978 storm has a special place in Connecticut weather lore. 

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<![CDATA[Snowstorm Bust - What Went Wrong]]>471781794Tue, 30 Jan 2018 18:24:32 -0400https://media.nbcconnecticut.com/images/160*120/DUyvSnJV4AEOE7X.jpg

When I woke up around 8 a.m. and checked my phone to see how the storm "performed" at least one or two expletives rolled off my tongue. You can use your imagination. My forecast at 6 p.m. Monday was 0"-1" of snow - and by now we know how that turned out. By 11 p.m. I was mentioning at least 2" in eastern Connecticut but I had an uneasy feeling for sure. Here are a few of the reasons why the storm dropped up to 7" of snow in New London County.

How much dry air?

One of the issues all along with this storm was how much dry air there was above our heads and whether that dry air would stay in place. For nearly 12 hours radar showed precipitation falling over Connecticut on Monday and barely a flake made it to the ground. We call this virga - precipitation that dries up before reaching the ground. 

Even at 11 p.m. last night under very heavy bands on radar we were struggling to get even moderate snow to the ground due to the dry air aloft. This sounding from Long Island at 7 p.m. last night shows the pocket of dry air about 7,000 feet up. This was one of the bigger forecast challenges.

As it turned out the atmosphere rapidly saturated south and east of I-84 resulting in heavier snow making it to the ground. Farther northwest in Litchfield County and even in places like Enfield the dry air held firm with only about a coating of snow.

Where's the lift? 

To figure out where precipitation will fall (rain, snow, etc.) you need to figure out where there will be rising air. As air rises it cools and you eventually get clouds and precipiation. In general, the faster air rises the more precipitation there will be. 

In storms like this we look for something called frontogenesis about 10,000 feet up. As a front develops (something separating warmer air from colder air) air begins to rise rapidly along this frontal surface. This front is sloped - imagine it slicing through the atmosphere on an angle with air being forced up this "slope". This is generally the holy grail for winter storms. 

As it turned out this set up from central Long Island to eastern Connecticut to central Massachusetts with persistent bands of heavy snow. 

To show this in an easier to digest way check out the High Resolution Ensemble Forecast from midday Monday.  All 4 of the current members showed less than 1" of snow in Connecticut (even eastern Connecticut) with the 4 older members showing an inch or two. There was a dramtic cut back from Sunday night to Monday midday. 

In general, our high resolution models tends to resolve these "snow bands" well. While they struggle with the location they frequently sniff out their existence. In this case - nothing!

OK, So there's lift and not much dry air. How much snow will we get?

After getting questions 1 and 2 wrong with this storm (though they are related) the third one proved the most vexing. With a band of stronger lift with little dry air left the snow band went to town.

The strongest lift (upward vertical motion) was occuring at a temperature of about -15C. Believe it or not this is critical. This is the temperature at which snow flakes grow most efficiently (i.e. more bang for your buck with snowflake production) AND the favored snowflake is a dendrite. Dendrites are the beautiful ornate snowflakes that pile up very quickly and easily as they the branches of the crystals get tangled with one another. 

Typically, 1" of liquid water yields about 10" of snow. Put another way if you take 10" of snow it would melt down to about 1" of water. Not this storm!

In Stonington 7" of snow fell this morning. That 7" of snow melted down to about 0.25" of liquid! That's a 28:1 snow to liquid ratio! Getting a ratio that high in southeastern Connecticut with 7" of snow is very, very, very unusual! 

Lessons Learned

As much as a big forecast bust is personally disappointing to a meteorologist it's part of the job. Part of the excitement of weather to me is its unpredictability. More often than not the forecast is right but sometimes it's not - and sometimes like today it's wrong in a pretty spectacular fashion. 

This turned out to be a perfect storm of errors. Getting one of the key points wrong resulted in a dramatically different result. 

The nice thing about the weather is that there's always a new storm on the horizon. Let's hope the forecast is better!

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<![CDATA[Storm Next Week?]]>471194403Thu, 25 Jan 2018 21:37:45 -0400https://media.nbcconnecticut.com/images/213*120/Evening_Forecast_Jan_25_2018_1200x675_1146162755623.jpg

A number of storms we've had this winter looked like "non-events" 4 or 5 days out only to track farther and farther west on our computer models until the event occured. It's been a pretty remarkable trend!

Next Monday and Tuesday we've got another offshore storm with a pattern that's conducive to a New England snowstorm. It's not perfect but it shows potential. Most of our computer models don't show much right now locally but do get close enough to raise some eyebrows. Check out the evening GFS ensembles for accumulated snowfall and you can see quite a spread in possible solutions - ranging from 0" to nearly 7" in Hartford. The mean and the operational run (the highest resolution member) are close to one another with at least some light snow.

As of right now there appears that the storm just can't get its act together with a small difference in timing between two jet streams that are unable to phase in time. The most likely scenario would be light rain to light snow. But, man it's close. Given the trend for storms this year tracking farther northwest than their 4 and 5 days forecasts it's worth watching this one closely. 

As always - stay tuned!

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<![CDATA[Ice Jam Flood Threat]]>470606223Mon, 22 Jan 2018 21:55:36 -0400https://media.nbcconnecticut.com/images/180*120/image1012218erin.jpeg

Around 1" of rain is expected to fall across the state Tuesday. With no snow on the ground to melt this rain would not normally be enough to result in flooding but this may be a different case. Existing ice jams on the Connecticut River and the Housatonic River may cause issues as river levels begin to rise as the rain runs off into the state's larger rivers.

Over the last few days we have seen river levels drop across the state but the river levels remain stubbornly high upstream of the two main ice jams in the state at the East Haddam Swing Bridge and near the Kent School. The concern tomorrow is heavy rain causing river levels to rise and forcing the large ice jams to move around some. These ice jams are very unpredictable and if the jams were to reconfigure themselves in a way that the river flow was constricted even more than flooding upstream may begin again. 

It's hard enough to predict how much rain will fall and how much rivers will rise. Trying to figure out how chunks of ice will move and if they'll get stuck again on river banks or obstructions like bridges is next to impossible. While serious flooding seems unlikely it cannot be ruled out and we'll have to watch it closely.

One other possible issue on Tuesday is strong gusty winds. At this point gusts over 45 mph seem unlikely. Very powerful winds just a few thousand feet above our heads (75+ mph) will be roaring and should remain bottled up there. A strong inversion means there is a strong stable layer near the ground which effectively prevents the high momentum air from mixing down to the surface. Things such as thunderstorms or gravity waves can start to do funky things but at this point damaging wind gusts do not seem likely. 

Photo Credit: Erin Reemsnyder
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<![CDATA[Weekend Ice Jam Threat]]>468897433Thu, 11 Jan 2018 22:41:50 -0400https://media.nbcconnecticut.com/images/180*120/ICE+Dam+AdobeStock_82001887.jpeg

It's been a while since we had a serious ice jam flood in Connecticut. In January 1994 a rapid January thaw following a bitterly cold month caused all sorts of problems. As the snow melted and the rain fell rivers rose rapidly and huge chunks of ice broke apart across the state. 

On the Pomperaug River in Southbury a 2.5 mile ice jam lasted for weeks sending the river surging into neighborhoods. In Baltic the Shetucket River was jammed for about a mile flooding 75 homes and businesses in the Sprague village. 

The National Weather Service estimated nearly a foot of ice is on our local rivers which is unusual for Connecticut. This is the kind of ice you'd expect to see in Vermont, New Hampshire or Maine. Heavy rain and melting snow means ice jams are unsually likely in Connecticut. Hopefully these ice jams occur in rural areas or, even better, don't occur at all!

Be on the lookout for sudden rises in rivers over the weekend as ice jams can develop across the state. 

Photo Credit: salman2 - stock.adobe.com]]>
<![CDATA[We Did It!]]>468522213Tue, 09 Jan 2018 22:48:54 -0400https://media.nbcconnecticut.com/images/213*120/Generic+Plate+6.png

After 14 days of below freezing temperatures the streak ended today. For the first time since Christmas the mercury reached 32 degrees. Spending this long below freezing is unusual. At the shoreline at Bridgeport this is the longest sub-32 stretch on record while in the Hartford area this tied for the 8th longest stretch below freezing. 

Not surprisingly we've seen a tremendous amount of ice develop on Long Island Sound, lakes, ponds and rivers. The Sound doesn't have as much ice on it as it did during the record 2015 cold snap partially because the first week of the cold snap was lost cooling off the sea surface temperatures (the water temperature at New Haven Harbor was 43F on Christmas, for example) down to freezing. Eventually as the temperature dropped below freezing the salt water began to freeze.

Going forward with a round of heavy rain and warmer temperatures Friday and Saturday we need to be concerned about ice jam flooding on rivers and flooding of basements given how frozen the ground is. 

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<![CDATA[Thursday Snowstorm]]>467768273Tue, 02 Jan 2018 22:45:03 -0400https://media.nbcconnecticut.com/images/213*120/Evening_forecast_for_January02th2018_1200x675_1127962179725.jpg

Here's a quick breakdown of what we're expecting from Thursday's snowstorm.

Snow begins: 1 a.m. - 4 a.m. Thursday

Peak of the snow: 8 a.m. - 2 p.m. Thursday

Snow Ends: Gradually during the evening

Peak Winds: Gusts to 50 mph Thursday afternoon and evening

In terms of accumulation we're going with a blend of the more amped up mesoscale computer models (like the NAM and RGEM) and the more subdued global models (like the GFS and ECMWF). In fact this blend results in a forecast that is pretty close to both the GFS and European ensembles.

Could this change? Of course! This storm is extremely powerful and only a subtle wobble to the west would result in a much different kind of storm locally. This storm will feature powerful thunderstorms near its center and the pressure will drop to very low levels (likely between 950 and 960mb). We have seen some of our high resoltion guidance (guidance that can explicitly resolve thunderstorms) print out incredible snowfall back in Connecticut - some on the order of 1-2 feet. While these models can occasionally be right they also sometimes result in feedback loops that create incorrect (and overly extreme) solutions.

Given the intensity of this storm it's worth watching closely. Small changes will make big differences in the outcome here in Connecticut.

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<![CDATA[Cold Snap to Close Out 2017]]>466697853Wed, 27 Dec 2017 07:54:12 -0400https://media.nbcconnecticut.com/images/213*120/DR_7a0UX0AIFLsY.jpg

The severity of this week's cold snap isn't particularly impressive but what is impressive is the expectation that this cold snap has some legs. We're currently forecasting temperatures to remain below 32 degrees for the next 10 days!

The initial peak of the cold will be on Thursday with wind chills between -10F and -20F. Beyond Thursday's cold the question is will we get any snow this weekend. An upper level disturbance swinging through the Great Lakes is going to initiate a storm off the northeastern U.S. Most of our computer models keep this storm well offshore but there are some differences. If we compare the GFS and the European model you can see how different the strength and orientation is of the upper level disturbance.

The Euro and the GFS models are a world apart in terms of how they handle the upper level energy. The Euro is amplified (big dip to the south) and snowy while the GFS is much flatter. There's a huge difference in sensible weather here between the two. Looking at the GFS ensembles I see some support for the more amplified Euro with many ensemble members producing at least some snow in Hartford.

The bottom line is we'll have to watch this system carefully as our models are still having a lot of trouble figuring out what it's going to do. Given the amount of cold around the snow has the potential to be quite dry and fluffy which tends to allow it to pile up quickly.

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<![CDATA[Ice, Rain, and Snow]]>466021943Fri, 22 Dec 2017 21:47:19 -0400https://media.nbcconnecticut.com/images/213*120/Evening_forecast_for_December22th2017_1200x675_1122774083992.jpg

What a mess out there this evening. Freezing rain across the state (as far south as New Haven) as resulted in a glaze of ice on untreated surfaces across Connecticut. We have reports of accidents in eastern Connecticut and I'm sure countless people have fallen on sidewalks, driveways, and decks tonight!

Unfortunately our freezing rain is going to continue into Saturday morning across the interior. Our computer models are almost always too quick to scour out cold dense air wedged in the valleys and this is no expection. The evening NAM computer model which handles these setups the best of our models shows temperatures near 32 degrees as late as early afternoon around Bradley Airport right at the ground.

This is a classic case of cold air stuck in the Connecticut River valley (hills of 1,000 feet on either side) that is reinforced by a gently northerly drain of air from Massachusetts. One other area to watch is New Haven. Cold air can drain easily down the Quinnipiac River and get trapped between Totoket Mountain in North Branford and the Metacomet Ridge (West Rock). I wouldn't be surprised to see freezing rain continuing through early morning around New Haven thanks to the northerly drain. 

By Christmas it looks like we may see snow! A late-developing storm on the leading edge of much colder air moving in from the west. Our first cut at snow totals is 3-6" northwest of Hartford and 1-3" southeast of there. There will be a rain/snow line with this storm and there's also some uncertainty how quickly it begins to develop. Our preliminary thinking is a start time between 10 p.m. and 1 a.m. Sunday night/Monday morning and an end time 6 a.m. to 9 a.m. Monday. We'll be watching it closely and update as needed. 

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<![CDATA[Period of Ice Friday & Saturday]]>465564843Wed, 20 Dec 2017 22:26:49 -0400https://media.nbcconnecticut.com/images/213*120/Evening_forecast_for_December_20th2017_1200x675_1121099331754.jpg

It doesn't look like a big storm but it does look messy. Occasional snow and some ice during the day Friday transitions to a steady period of precipitation Friday evening and night. 

The problem is going to be the predominant precipitation type Friday night is going to be freezing rain. There will be a large layer of above freezing air above our heads that will turn snow flakes to rain. However, near the ground, temperatures will be around or just under 32 degrees across the interior which will result in freezing rain. Rain will freeze on contact with untreated surfaces. 

With high pressure to the north and a relatively weak system moving in from the west is always problematic this time of year. Our computer models tend to do scour out low level cold in the valley too quickly and generally don't resolve the extent of low level cold particulalry will. The above sounding (off the NAM computer model) shows a large area of above freezing temperatures with a very shallow zone of cold air. 

Eventually the warmer air will win out and the freezing rain Saturday will transition to plain rain. In terms of impact I'm not currently expecting enough ice to cause issues with trees and power lines but the ice will make untreated surfaces slippery. The best chance for icing is across the interior but a brief period of icing as far south as New Haven is possible as well. 

And then there's Christmas. A tremendous amount of model spread still exists for a storm on Christmas Day. Some solutions are east and offshore while others are overhead (resulting in rain). There is certainly the possibility for accumulating snow but it's too soon to say anything with much certainty. 

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<![CDATA[The Dreaded Wintry Mix]]>465323373Tue, 19 Dec 2017 22:21:31 -0400https://media.nbcconnecticut.com/images/213*120/Launch+10+Day+3_121917.png

A wintry mix. A mixed bag. A kitchen sink storm (a Bob Maxon-ism). Friday could be all of the above. 

A warm front pushing into southern New England along with a cold high pressure to the north is a bad combination. Some snow, some sleet, some freezing rain and some rain. How much of each remains the question. In terms of snowfall at this point the odds of >1" of snow remain low - about 1 in 4 or so. 

What you can't see, however, is the potential for icing. A cold high pressure (strengthening) to our north over Maine, Quebec, and New Brunsiwck should provide a nice wedge of cold over southern New England.

The analog guidance is showing high probability for over 3 hours of freezing rain throughout southern New England. Given the look and setup this isn't a surprise.

At this point we're expecting a period of snow, sleet and freezing rain Friday through Saturday morning - gradually changing to rain. Some ice accretion is possible on roads, power lines, trees, etc. 

At least initially what we get on Friday should be light but enough to cause issues on the roads. There may be a brief break Friday evening/night before another round of icing across the interior Saturday morning.

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<![CDATA[Challenging Christmas Forecast]]>465068783Tue, 19 Dec 2017 14:31:38 -0400https://media.nbcconnecticut.com/images/160*120/gfs_pr6_slp_t850_ma_29.png

To say that there's a lot of uncertainty about the Christmas forecast would be a big understatement. A huge push of Arctic cold will be moving south out of Canada while moisture will be moving northeast out of the Gulf of Mexico.

Earlier I tweeted about the difference in our computer guidance for 12/25. Obviously it's a lot more complex than just picking a random computer model out of thin air but the bigger take away is that there is a tremendous amount of spread in possible outcomes.

Looking a bit more closely at our afternoon guidance we can see a few things. The most important part of the forecast is how far east the storm coming up the coast gets - for instance an offshore storm is more likely to produce cold and a wintry mix here in Connecticut while an inland storm (commonly referred to as an inland cutter) would bring rain. My gut feeling is a warmer/western solution is most likely with mainly rain. Below are the GFS aned European Ensembles (both models are run 20 and 50 different times, respectively, to produce a range of possile outcomes). 13 of the 20 GFS ensembles produce more than an inch of snow in Hartford on Chritsmas while about 25% of the European Ensembles do.

The current forecast I have for Bradley Airport is 38F and rain on Christmas but this may certainly change in the coming days. Stay tuned!

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<![CDATA[I've Got a Bad Feeling About This]]>464277933Thu, 14 Dec 2017 23:03:02 -0400https://media.nbcconnecticut.com/images/213*120/DRDLbkIW4AAu4772.jpg

I was looking forward to a quiet Friday at the office. What was a total non-event 12 hours ago suddenly looks a lot more interesting tonight. While it's still possible we only get a minor amount of snow (flurries or snow showers) there is a rising possibility of an accumulating inch or two along the shoreline around sunset Friday. 

A weak disturbance racing east from the Plains is going to be off the Mid Atlantic Friday evening. For the last several days we thought we could see a few flurries here but not one piece of model guidance expected more than that. Starting around midday we saw a few wobbles north and this evening a few models made some fairly alarming jumps north for a 24 hour forecast. Take the Short Range Ensemble Forecast. Look at the huge jump northwest over the past 3 runs with precipitation for Friday evening.

One reason why this bears watching is that much like this morning's snow the snow Friday night looks quite fluffy with cloud temperatures around -15C (or about 5F)!

These kind of systems are my least favorite. Very sneaky, hard to forecast, and have the potential to impact people's plans. At this point I'd be ready for some accumulating snow after about 4 p.m. Friday and know that the evening commute may be impacted especially in southern Connecticut. The extent of impact is still unclear. 

We'll keep you updated as things develop quickly. 

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<![CDATA[Fluffy Morning Snow]]>464030313Wed, 13 Dec 2017 22:19:42 -0400https://media.nbcconnecticut.com/images/213*120/DQ9lgA0XUAETyGU.jpg

A period of steady snow will produce a bit of accumulation Thursday morning across the state. In the Hartford area only a coating to an inch is expected and along the shoreline 1"-3" is possible. This is certainly not a big deal but the timing isn't best as the snow will be falling during the morning commute. 

One reason why we think this storm may produce higher totals than we initially thought is because of a very high snow:liquid ratio. What I mean by that is that only 0.1" of liquid could produce 2" of snow (a 20:1 ratio!) which is a pretty impressive fluff factor. 

The way snow gets fluffy is when temperatures are cold and the snow flakes are produced in clouds that are between -12c and -18c. Snow flake production is maximized at this temperature and the flakes that form at this temperature tend to pile up readily. 

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<![CDATA[Thursday Morning Snow]]>463781943Wed, 13 Dec 2017 12:05:21 -0400https://media.nbcconnecticut.com/images/213*120/Model+RPM12+Precip+Cloud+Floater121217.png

Wednesday Morning Update: There's a smidge more moisture with this storm and it is going to track a bit closer to the coast. Because of that the odds of 1" or more of snow have increased along the shoreline and there is certainly a risk for a heavy coating as far north as the Massachusetts border. I expect a slippery morning commute in many locations. We'll have to update the snow accumulation forecast to show a bit more accumulation today. 

Our coldest air of the fall so far is streaming into Connecticut right now. Some evening snow showers and wind chills near zero by tomorrow morning will be a pretty big shock after some towns in southeastern Connecticut approached 50F today!

With the cold in place the next system we're watching is a fast moving, and moisture starved, clipper racing underneath southern New England. The question is whether any of whatever moisture there is can scoot far enough north to clip southern Connecticut first thing Thursday. 

Even a little bit of moisture may be enough to result in some minor accumulation. One reason for that is that this snow has the potential to be very fluffy and can accumulate readily. Even a small amount of moisture could result in a fluffy inch. Below the yellow highlighted area off the NAM computer model shows cloud temperatures between -12c and -18c and this is important!

When snowflakes grow around -15c they grow as dendrites (the beautiful and ornate crystals) and those dendrites grow efficiently and accumulate readily! This snow crystal morphology diagram shows which crystals grow at which temperatures. 

The combination of efficient snowflake growth AND snowflakes that are able to accumulate with a good "fluff factor" this could be a case where a ratio of liquid water to snowfall may be closer to 15:1 or 20:1 as opposed to the typical 10:1. With only a few hundreths of an inch of liquid the difference between a 10:1 ratio and a 20:1 ratio is important to the forecast.

So the bottom line is that some fluffy accumulation is possible around the morning commute Thursday - especially along the shoreline. The key will be how much moisture will this storm have with it AND how far north the system gets. Not a big storm by any means but with very cold temperatures I have no doubt snow will accumulate on highways and roads first thing Thursday.

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<![CDATA[First Snow Storm of the Season]]>462916803Sat, 09 Dec 2017 00:09:08 -0400https://media.nbcconnecticut.com/images/213*120/Weather+Alerts+1_120817.png

Winter storm warnings have been issued for parts of Connecticut ahead of our first winter storm of the season. I've nudged up snow totals a bit tonight to account for the potential of 7" or 8" of snow in parts of eastern Connecticut.  That said, most towns will see around 5" of snow. 

Tonight, we're dry. You can see on the evening weather balloon launch from Long Island a pocket of very dry air in the lowest 10,000 feet of the atmosphere. No snow is going to make it through that! 

Eventually, however, the snow will come. The offshore moisture will surge back northwest and that dry layer will quickly moisten up. We're quite confident in where the storm will track. Now that the general setup is clear we need to lock in the snow forecast - and this is a quick and dirty look at how I do it.

Not much has changed since yesterday with the storm other than a slight uptick in the amount of forecast precipitation. The GFS shows between 0.3" to 0.6" of liquid across the state while the NAM and Euro shows between 0.4" and 0.7" of liquid. These numbers seem reasonable to me given the storm's movement and intensity.

Now that we're reasonably certain how much liquid water will fall from the clouds we need to figure out the ratio of snow to liquid water. Not all snow flakes accumulate at the same rate! Some snowflakes accumulate readily while others are dense and accumulate slowly. In fact, even without melting, snow:liquid ratios can range from 6:1 to 40:1! Life would be much easier if I could just forecast how much liquid water would fall! 

Most snowstorms in Connecticut manage around 10" of snow to 1" of water, or 10:1 as we call it, and I'm expecting this one to be close to that.

My rule of them is take your forecast liquid and always go 10:1 unless you have convincing evidence to go higher (there are times where I'll to 15:1 or 20:1). The reason we're expecting an "average" ratio is that the ice crystals in the clouds will be growing at temperatures warmer than -12C. This isn't ideal for heavy snow.

Ice crystals growing around -10C or -8C will give us snow crystals like plates and columns. If you wear black gloves outside and catch some snowflakes you'll be able to see them! When snowflakes grow around -15c they grow as dendrites (the beautiful and ornate crystals) and those dendrites grow efficiently and accumulate readily! This snow crystal morphology diagram shows which crystals grow at which temperatures. I'll leave vapor pressure out of this lesson for now.

The snow begins Saturday morning (around daybreak at the shoreline) and continues through the afternoon and evening. While the intensity will never be particularly strong there will be bands of snow that last off and on through the night. In fact, I wouldn't be surprised to see a bit of fluffy snow early Sunday morning as an upper level disturbance swings through and temperatures drop.

Enjoy the snow!

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<![CDATA[Thursday PM Update: Saturday Snow]]>462666133Fri, 08 Dec 2017 01:43:04 -0400https://media.nbcconnecticut.com/images/213*120/DQeMJ-cXUAAeTLp.jpg

Late Thursday night update: Our first look at the late computer guidance indicates no backing off some of the earlier numbers. With slightly better agreement and higher confidence I've increased the earlier forecast (released at 3:30 p.m.) from 2"-4" to 3"-6". 

Earlier Update: When there's snow in the forecast everyone wants to know what will happen in their town. They want a deterministic forecast. For example, the snow begins at 7 a.m. and Hartford will pick up 3.8" of accumulation. Unfortunately meteorology doesn't work like that. We really work in probability and try to determine which outcomes are most likely and which are least likely.

That said, not all events are created equal. Some storms are easy to forecast while others are more challenging. Some times we're very confident in what's going to happen and other times we haven't a clue. It's really important for me to be as transparent as possible and tell people what's most likely, what's possible, and what's least likely. I'll also tell you when I have no freaking idea what's going to happen. 

One way to determine how certain or uncertain a forecast is by looking at computer model ensembles. We basically take one computer model and run it 20 different times with a few little tweaks. Sometimes they're tightly clustered around one solution (high confidence) or all over the place (low confidence). Last night's GEFS had 6 members showing more than 1" of snow with 14 of them had less than 1". The most likely scenario (based on this model) would be an unimpressive event BUT there were some pesky outliers that would indicate a plowable snow. In fact more than 25% of them were showing something of note.

As luck would have it those outlier solutions appear to be the ones that will be correct. Starting with the morning computer guidance that comes out between 4 a.m. and 6 a.m. everything started trending west. And that west trend hasn't stopped. 

One possible reason for this is that there are two pieces of energy that will come together for this storm. One over the Gulf of Mexico and one that was over the Arctic Ocean - not far from the North Pole. The latter disturbance is in a "data desert" - there aren't many weather observations up there! Now that the disturbance is over Canada it is being sampled more accurately and that may be the reason why we're seeing a jog west in our computer guidance. If only polar bears could launch weather balloons.  

Take a look at the jump west in the MEAN snowfall from the GFS ensembles. Last night the mean of the 20 members was about 1" for Hartford and now it's over 6". There has been a clear jump west toward those outlier solutions. This is why unlike some local meteorologists we never wrote this storm off. Some were flopping around giving an "all clear" but we didn't take the bait with those pesky outlier solutions floating around.

So what to expect going forward? The first thing we need to figure out is if this west trend is going to stop. Right now I have 2"-4" of snow statewide but that number may be conservative! If the storm continues pushing to the west we will have to increase our forecast. 

Once we get the general setup down with how far west the best lift and moisture will make it we can start to get cute with pinning down locations of heaviest snowfall in the state. Where will narrow bands of heavier lift and snow setup? Will some parts of the state see "fluffier" snow due to better growth of ice crystals in the cloud? By tomorrow we will start doing that. 

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<![CDATA[On Ryan's Radar: Weekend Snow Update]]>462428283Thu, 07 Dec 2017 11:59:04 -0400https://media.nbcconnecticut.com/images/160*120/gfs_tprecip_nyc_14.png

Thursday Morning Update: A bit of a wobble west on our overnight computer models indicates accumulating snow is becoming more likely. As shown above there remainsa a very tight gradient between a couple inches of snow and just flurries. We'll have to see if the overnight wobble west was the beginning of a trend or a burp. At least right now i'd prepare for some snow on Saturday afternoon through Saturday night. More details to come...

Wednesday Evening Update: A complicated forecast continues for this weekend across southern New England. Let's hope this isn't a sign of things to come this winter! The hardest part of the forecast is an exceptionally sharp western cut-off of the snow shield on Saturday. 50 miles is the difference between a flurry and a couple inches of snow.

While some of the operational runs have bounced back and forth the consensus forecast hasn't really moved with a glancing blow and some snow here in the state. As always, the devil is in the details. Take the afternoon GFS ensemble snowfall forecast. You can see 14 of the 20 ensemble members with less than an inch of snow in Hartford while 6 of the 20 with more than 1". Just like yesterday, odds favor not much snow but there are some outlier solutions that would bring a plowable snow as far west as I-91. Other global models such as the UKMet and Canadian show a more substantial snowfall here (basically what some of the GFS ensemble outliers show).

While everyone wants to know a specific snowfall forecast for their town it's simply too soon to give that. I wish I could! Some storms are more certain and some are more uncertain. This one falls in the latter category. 

The National Weather Service is very bullish on snowfall amounts (they tend to be much higher than other local forecasts) showing a nearly 50% chance of over 2" of snow. I think that is overstated quite a bit. Still, we can't write this storm off just yet. 

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<![CDATA[Chance for Weekend Snow]]>462192983Tue, 05 Dec 2017 22:54:41 -0400https://media.nbcconnecticut.com/images/213*120/DQTzVK5WsAAk8W0.jpg

The long awaited pattern change is here. The first shot for snow we have comes Friday night and Saturday morning. It's by no means a sure thing, however. Tonight during our evening newscasts I gave the system about a 1 in 3 shot of producing accumulating snow in Connecticut.

Here's the setup. A large area of moisture offshore along with a stationary front will be lurking nearby Friday night and Saturday morning. At the same time a jet stream disturbance will race north and may help nudge the offshore moisture back west. With enough cold air this would likely be snow in Connecticut. 

So what is going to happen? At this point I don't know. There is certainly some opportunity for this offshore system to back in a bit and deliver accumulating snow. In fact, the back edge of this system is giving our computer modeling a heck of a time. Check out the 20 GFS ensemble members (the GFS computer model is run 20 different times at slightly lower resolution top provide a reasonable range of solutions) below. You'll see accumulated snowfall plotted for Hartford here (each line indicates one of the ensemble members with the thick black line being the mean). 

This shows a significant spread with how far west the offshore moisture will get. Anywhere between 0.0" and nearly 8" of snow! Other computer models don't show quite as much spread with a more minor event.

So for now it's sort of wait and see. How sharp can the jet stream disturbance get and how far west the offshore blob can move. Until the model spread shrinks all options are on the table from no snow to nuisance snow to plowable snow. 

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<![CDATA[Winters are Heating Up]]>460910763Wed, 29 Nov 2017 23:31:04 -0400https://media.nbcconnecticut.com/images/213*120/Ryan_Winter_Warming_1200x675_1106492995557.jpg

If you've lived in Connecticut for a certain amount of time you may have noticed winters are milder now than they were several decades ago. The data backs up what many people already know.

Check out the temperature increase in the Hartford area (officially Bradley International Airport) over the last approximately 50 years. In that time the average winter temperature has increased nearly 4 degrees. Every weather station with long terms records I examined as seen a similar trend locally.

It's not just Connecticut that's getting warmer. During December, January, and February which is meteorological winter virtually every climate division has experienced warming since 1970 in the United States according to our partners at Climate Central.

As levels of Carbon Dioxide rise in the atmosphere climate scientists are nearly certain that temperatures will continue to rise. Even in a warmer climate colder than normal spells of weather can and will still occur - though they won't occur as frequently as warm spells. 

You may be wondering if warmer weather means less snow. The answer, for now, is no. There has been no discernible trend in New England of decreasing annual snowfall and in some locations snowfall is actually increasing. While this may seem counterintuitve warmer air can "hold" more water vapor. More moisture in the atmosphere plus warmer sea surface temperatures offshore can result in more intense storms and at least over the last several decades more snow. 

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<![CDATA[Easing Into (Meteorological) Winter]]>460395743Mon, 27 Nov 2017 22:22:17 -0400https://media.nbcconnecticut.com/images/213*120/DPrx-H6X0AEBOLj.jpg

The end of November is not looking all that memorable for the weather department. The first few days of meteorological winter, which begins December 1, aren't looking too exciting either with temperatures within a few degrees of normal (we do get a nice warm up on Wednesday) and no big storms on the horizon. 

The reason for the quiet weather pattern this week locally, and more broadly across a good chunk of the United States, is a zonal jet stream flow. You can see no big dips in the jet stream and a fairly benign looking jet steam. Generally, big storms form when the jet stream buckles and large troughs and ridges appear.


Going forward, however, things do look a lot more interesting. Beyond the first week of December we see some fairly large changes to the jet stream. Check out the changes coming over the next 15 days. The first graphic here is the Day 1-5 European Ensemble height anomalies and the Day 11-15 forecast. What starts out as a zonal (generally west to east flowing jet stream over the Pacific and North America) becomes quite disturbed. 

The combination of significant high latitude blocking (not shown is a big disruption of the stratospheric polar vortex) and a huge change to the jet stream pattern over the Pacific should favor a much colder weather pattern. It would appear that a significant pattern change with chances for below normal cold and snow is a possibility around December 10th. How long this will last is a question.

While nailing a day 10 to 15 forecast is a challenge we are looking at the general weather pattern and not specific storm systems. What this "favorable" pattern means is that we will load the "atmospheric dice" to favor cold outbreaks and snow. I'd have my snow blower ready to go in about 10 days.

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<![CDATA[The Great Southeaster of 1950]]>459827853Fri, 24 Nov 2017 22:01:23 -0400https://media.nbcconnecticut.com/images/160*141/1950112518.gif

Connecticut meteorologists love talking about nor’easters but do you know about the state’s biggest southeaster? The “Great Appalachian Storm” of November 25, 1950 was one of Connecticut’s most violent wind storms on record. In some towns the wind speeds in 1950 were only exceeded by the great hurricane of 1938!

The storm was only of modest strength in terms of central pressure – 980ish mb. But what made the winds vicious was the 1050ish mb high near Maine. The freakishly strong pressure gradient produced violent southeasterly and easterly winds across New England. Here are some of the wind gusts recorded in Connecticut on November 25, 1950.

  • Bridgeport – 88 m.p.h.
  • New Haven – 77 m.p.h.
  • Hartford – 100 m.p.h.

The 70 m.p.h. "fastest mile" wind in Hartford remains the strongest wind recorded for the official Hartford records since observations began in 1904. The second highest value is 64 m.p.h. recorded during the October 3, 1979 tornado. In Bridgeport the sustained wind of 62 m.p.h. is one of the highest on record (since 1948) with the highest occurring during Gloria in 1985 at 74 m.p.h. sustained and two other higher wind speeds during the winters of 1964 and 1969. Note on record: 2-minute sustained winds replaced 1-minute sustained winds in 1995 and this record is "fastest mile" which is different anyway. 

For a non-tropical storm there’s no question in my mind that the 1950 southeaster was the most violent windstorm we’ve seen. The standardized anomalies from Richard Grumm at the NWS in State College shows a wide area of +4 standard deviation 850mb winds. That’s quite a low level jet! The winds reached 160 m.p.h. on Mount Washington in the core of that LLJ.

Looking at the reports from that day here in Connecticut temperatures in the warm sector came close to 60º with highs in the upper 50s in Hartford, Bridgeport, and New Haven. The unseasonably warm weather, when coupled with a a ripping low level jet, lead to enough turbulent mixing to mix down destructive winds – in some cases to 100 m.p.h.!

Here are some of the comments from the official weather bureau reports.

Hartford – “Of paramount interest in this month’s weather is the occurrence of “The Great Wind Storm of November 25, 1950″. Considering its great extent, extreme weather of various types, and its unusual meteorological character, this storm will be long remembered. At Hartford, E’ly winds averaged the amazing speed of 38 m.p.h. for the entire day of the 25th, and attained gust speeds of at least 100 m.p.h. on at least 3 occasions between 4:30 and 7:30 p.m..”

Bridgeport -” Storm of Nov. 25th worst since 1938. Station inundated with 4 to 5 feet of water.”

New Haven – “Severe southeast storm on 25th. Extensive wind and water damage to shore fronts. Many trees, wires, antennae down, roofs damaged. Max for 5 minutes: 50 SE at 1:55 PM (17 Hrs.), probably exceeded 8:00-9:00 PM. Fastest single mile: 57 SE at 1:56 PM (17 Hrs.), possible exceeded 8:00-9:00 PM. Gusts: 55 MPH at 1:35 PM; 66 MPH at 4:20 PM; 66 MPH at 7:40 PM; 77 MPH 5 second gust at 4:45 PM… 5 min. max record; fastest mile exceded in Sept. 1903.”

The strong winds produced widespread tree and power line damage across the state. The winds tore a roof off a dormitory at UConn and ripped shingles off roofs across the state. Several shoreline homes lost their roofs according to a Hartford Courant article from shortly after the storm.

The storm surge flooding was extensive on the coast. In New London the tide reached an impressive 7.58ft MLLW. The only storms higher in the last 100 years are the 1938 hurricane, hurricane Carol, and hurricane Sandy. In Stamford at the Hurricane Barrier the tide reached 9.5ft NGVD which was similar to Irene’s tide level.

Much like Sandy, the storm surge flooded large portions of New York City including the lower east side and Laguardia Airport. Sandy’s surge, however, was much more powerful in the parts of the City, like Staten Island and the Rockaways, with Atlantic exposure.

On the Connecticut shoreline houses, cottages, railroad tracks, and beaches were swept away. Newspaper accounts indicate that the sand was several feet deep on coastal roads and was removed by snow plows. Many people had to be rescued from their homes after refusing to heed evacuation orders.

This type of unusually deep system lead to unusually cold weather and extreme snowfall in the Appalachians and the Ohio River valley. The storm is one of the worst blizzards in parts of the country. Steubenville, Ohio recorded 44 inches of snow while the synoptic desert of Pittsburgh dug out from 30.5 inches of snow!

In the southeast U.S. the backside of the storm delivered a bitterly cold air mass. The mercury dropped to -3º in Atlanta, GA. Many observing sites saw their coldest November temperatures on record. 850mb temperatures reached an INCREDIBLE -20ºC over northern Georgia at 12z 11/25/1950.

Not very often do you see a -6 sigma 850mb temperature! The exceptional baroclinicity and phasing resulted in what amounted to one of the most impressive east coast storms of the 20th century.

While we frequently refer to the March 1993 storm as the “storm of the century” the November 1950 storm gives ’93 a run for its money. For east coast storms we really had 2 storms of the 20th century.

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<![CDATA[Looking Into December]]>459636923Thu, 23 Nov 2017 22:17:56 -0400https://media.nbcconnecticut.com/images/176*120/814temp.new112317.gif

The 10 day forecast I showed tonight on NBC Connecticut is about as boring as it gets. No big storms, no big cold shots, and just periodic bouts of above to well above normal weather. Zzzzzzzzzzzzzzzzzzzzzzzzzz.

But - beyond the firstw week of December is where things start to get a bit interesting. At the top of the article you can see the December 1-7 temperature forecast from the Climate Prediction Center. There are good odds we will be quite mild! After the 7th, however, our long range computer guidance (Euro ensembles in particular) shows a global jet stream pattern that would really load the dice in favor of snow and coldr. We've got a strong ridge of high pressure over Alaska and up into the North Pole which effectively dumps Arctic air into the northeastern U.S.

At the same time some remnant -NAO blocking remains over Greenland. This is certainly a look which should excite snow lovers.

Of course all of this assumes the Euro weeklies are correct! Lots can go wrong around and after week 2. The presence of high latitude blocking for several days on our long range models can't be ignored. I think there's a window around 12/10 that will need to be watched closely. Until then.... hibernation after Thanksgiving dinner is not a bad idea.

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<![CDATA[Nice Looking Thanksgiving Week]]>458964243Mon, 20 Nov 2017 22:59:17 -0400https://media.nbcconnecticut.com/images/311*120/euro112017.PNG

I love snow but not this week! Too many errands, too many travel plans, too much going on, and too much pressure for your friendly neighborhood weatherman! 

A few showers on Wednesday followed by cooler than average temperatures on Thanksgiving is about all we have of note this week. We'll take that. You can see some colder air diving south into southern New England on Thursday thanks to a dip in the jet stream.

The one thing I am watching closely is Sunday and Monday (11/26-27). A bigger dip in the jet stream coupled with a big ridge of high pressure over Greenland known as a -NAO is an intriguing setup. At this point not much is modeled but it's not a bad idea to keep an eye on this window.

We have colder temperatures and flurries currently in the forecast. Hopefully we won't have to change it!

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<![CDATA[Afternoon Hail ]]>458124073Thu, 16 Nov 2017 22:51:53 -0400https://media.nbcconnecticut.com/images/213*120/DOx_PuoXUAE2NzO.jpg

Beautiful clouds, hailstones, rainbows, and downpours. It was a fun afternoon for a weather geek! 

Cold air aloft produced a pocket of instability over Connecticut which lead to the stormy weather. About 10,000 feet up the temperature was close to -12C while the temperature near the ground was in the low to mid 50s. This was a classic setup for low topped thunderstorms with a fair amount of moisture above our heads.

The fact the storms were fairly isolated, shallow, and occured near sunset produced such vibrant colors and rainbows across the state. Check out this photo gallery for some of your amazing shots. This afternoon's weather was pretty sweet :) 

Looking forward our next storm approaches this weekend and with it comes some gusty wind and another round of rain. At this point it looks like most of the rain will be Saturday evening through early Sunday morning. A well timed rain event! There is the potential for strong wind Sunday on the backside of the low and a low risk for tree and power line issues.

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<![CDATA[A Look Ahead to Thanksgiving Week]]>457589403Tue, 14 Nov 2017 22:33:48 -0400https://media.nbcconnecticut.com/images/160*120/eps_t850_anom_noram_216.png

At first glance the weather pattern for Thanksgiving week is a concerning one. A colder than normal pattern thanks in part to an infamous "NAO block". Many of our big snowstorms are associated with a negative North Atlantic Oscillation of -NAO and we have that next week!

Before we get too far ahead of ourselves there's a big reason why we shouldn't be too worried. While a sprawling ridge of high pressure blocks up the jet stream over Greenland and Baffin Bay (the -NAO) the jet stream configuration over Canada and the United States isn't too ideal for snow here. The biggest reason why is that the ridge of high pressure that stretches from the Four Corners through North Dakota is a bit too far east and it's too positively tilted (i.e. tilting eastward as you head poleward).

Given this look it's not a surprise that there's not much in the way of snow or coastal storminess modeled. While a -NAO can be a huge help for getting a big snowstorm in New England it doesn't always mean we'll get snow. In this case other factors upstream in the jet stream will preclude this -NAO as currently modeled from producing. In fact, in the 6-10 day period not one out of 51 European ensemble members have significant snow in Connecticut! 

Can things change? Of course. A slightly different orientation of that ridge axist o the west or even a change in location could allow things to get more interesting. More spacing between the ridge axis and the -NAO block would give disturbances more opportunity to amplify and smack us. Things are just spaced too close togther right now.

For now, I'm cautiously optimistic the Wednesday-Friday period around Thanksgiving will be chilly but not too stormy. Stay tuned!

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<![CDATA[Overnight Black Ice?]]>457336643Mon, 13 Nov 2017 22:01:05 -0400https://media.nbcconnecticut.com/images/160*120/hrrr_ref_neng_10_01.png

Dropping temperatures and a bit of low level moisture means a few towns could see a bit of black ice developing later tonight. While it certainly doesn't look like a big deal some towns could get a big slick.

This sounding from the NAM shows a pocket of low level moisture with near 100% relative humidity. While it is below freezing the coldest the clouds get is only about -2 or -3C which means they'll be ice free. This can result in pockets of freezing drizzle. 

Beyond Tuesday the weather pattern remains active but not too active. A bit of rain on Thuesday and more rain on Saturday. There is a chance for something wintry around Thanksgiving with a brief -NAO (North Atlantic Osciallation). Not much else to say about it now other than that we're watching it! 

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<![CDATA[NBC Connecticut Names Ryan Hanrahan Chief Meteorologist]]>457222893Mon, 13 Nov 2017 17:51:50 -0400https://media.nbcconnecticut.com/images/213*120/Ryan+Hanrahan+Nov+2017.jpg


HARTFORD, CT – NBC Connecticut / WVIT today announced Ryan Hanrahan as the First Alert Weather team’s new Chief Meteorologist, effective immediately. He will deliver real-time weather forecasts for the station’s weekday evening newscasts from 4 p.m. to 6:30 p.m. and at 11 p.m.

“Ryan delivers accurate, no-nonsense forecasts. I am confident he will thrive in this new role,” said Susan Tully, President and General Manager of NBC Connecticut. “His expertise and Connecticut roots blend to provide an unmatched knowledge that our viewers can trust.”

“Becoming a Chief Meteorologist in Connecticut has been a dream of mine since I was a kid growing up on the shoreline,” added Hanrahan. “I’m thrilled for this opportunity and excited to continue to share my love of weather and science with our viewers and in my home state.”

A native of Guilford, Connecticut, Hanrahan’s interest in weather was sparked by the 1989 tornado in Hamden, as well as hurricanes Gloria and Bob. After graduating with a bachelor's degree in Meteorology from Pennsylvania State University, he worked at WNYT, the NBC affiliate in Albany, New York. Hanrahan joined NBC Connecticut in 2005, after studying atmospheric science in graduate school at SUNY Albany. During his tenure at NBC Connecticut, Hanrahan has forecasted many of the state’s biggest storms including hurricanes Irene and Sandy, the October snowstorm of 2011, the blizzard of 2013 and the 2011 tornado in nearby Springfield, Massachusetts. In 2016, he was awarded a New England Regional Emmy in the “Weather Anchor” category in recognition of his weather forecasts and coverage.

About NBC Connecticut

Owned by NBCUniversal, NBC Connecticut / WVIT serves its audience with local news and weather information across multiple platforms, including more than 40 hours of newscasts each week on WVIT, news segments on CT COZI TV and online at NBCConnecticut.com. The station is Connecticut’s leader with Facebook and Instagram followers and provides mobile users on-the-go breaking news updates and weather information through a customized application. NBC Connecticut’s commitment to excellence in journalism has been recognized with numerous Emmy Awards, and the prestigious Peabody Award and Alfred I. duPont-Columbia University Award.


<![CDATA[Winter Cold]]>456755453Fri, 10 Nov 2017 22:31:16 -0400https://media.nbcconnecticut.com/images/213*120/DOUSiFHWkAEH1yQ.jpg

It's a cold night across the state with temperatures dropping through the 20s. We're going to be close to record lows by morning but may fall just short.

The cold shot peaks by morning and temperatures will moderate over the coming days.

Most of the next week looks pretty quiet. I don't see a whole lot to get excited about through next weekend. What we call a "zonal flow" will exist across the most of the Lower 48 through next week which will keep temperatures fairly close to normal and preclude any big storms from forming nearby.

By next weekend, however, our zonal flow becomes much more amplified. A large blocking ridge over Greenland which flips the North Atlantic Oscillation to negative. This will increase our chances for stormy weather and possibly even some snow before Thanksgiving. 

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<![CDATA[Timing out the Tumbling Temperatures]]>456480743Fri, 10 Nov 2017 13:44:26 -0400https://media.nbcconnecticut.com/images/213*120/cms989.jpg]]><![CDATA[First Flakes of the Season]]>455980503Tue, 07 Nov 2017 22:12:47 -0400https://media.nbcconnecticut.com/images/213*120/DOEr8ETXkAAa7H4.jpg

As expected rain has transitioned to a mix of rain and snow in the hills and some towns have even flipped to all snow. A combination of dry low level air resulting in evaporational cooling and a slow drain of colder air from the north. 

No accumulation is expected (on the roads at least) though I can't rule out a slushy coating in some of the high hill towns such as Norfolk, Colebrook, and Hartland. Even Wolcott at about 1,000 feet could see a slushy coating. As always, dual polarization radar was an incredible tool in tracking the the height of the above freezing level in the clouds. Radar allows us to pick up where melting snowflakes are occuring. 

Beyond tonight the big story is going to be a blast of Arctic cold moving in on Friday. A brief but impressive surge of cold air will send wind chills into the single digits and teens by afternoon. A big change from our record warm October! 

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<![CDATA[Some Arctic Chill]]>455711463Mon, 06 Nov 2017 22:00:31 -0400https://media.nbcconnecticut.com/images/160*120/gefs_t850a_conus_17.png

A blast of Arctic cold on Friday looks very impressive. Temperatures in the 30s and gusty winds will result in wind chills in the teens. Ouch. Before we get there we've got a minor issue on Tuesday. 

A weak wave of low pressure will move south of southern New England Tuesday evening. There's some question exactly how much moisture will move in AND how dry it will be near the ground.

The dry air near the ground is key to the forecast. We know the clouds above us will be producing snow - the question is whether that snow will make it to the ground. If the air is too dry (as the sounding above off the GFS shows) the snow will sublimate or dry up before reaching the ground.

If the dry air near the ground isn't too dry and better moisture and lift moves in aloft the dry air will allow the atmosphere to cool through evaporative cooling and will likely be cold enough for a bit of snow - or at least some rain mixed with snow. The NAM sounding above in Hartford shows that potential with the dry layer being wiped out. While quite unlikely we can't rule out a slushy coating in the hills but this is not currently in the forecast.

Beyond Tuesay evening's minor excitement the big story will be the big cold moving in on Friday. At this point the GFS MOS is printing out a remarkable 14F low on Saturday morning with temperatures in the 30s on Friday. 

While we're currently forecasting 22F this kind of cold is unusual for early November. The temperature has only reached 20F of lower 19 times since 1905 in the Hartford area prior to November 11th. In fact if the 14F for Hartford verified it would be the second coldest temperature on record for so early in the year. Only November 11, 1956 would be colder at 12F.  The last time temperatures reached the teens this early in the fall was November 10, 2004. Stay tuned - and stay warm! 

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<![CDATA[A Cold Shot!]]>455066283Fri, 03 Nov 2017 20:37:53 -0400https://media.nbcconnecticut.com/images/160*120/gefs_t850a_noram_29.png

After the warmest October on record it looks like we may see a legitimate shot of cold air - though it may only last for a day or two. Most of our computer models are picking up a brief Arctic shot next Friday and Saturday with cold air pouring down from southeastern Canada. 

This isn't a big surprise. For a while our long range models have shown a return to more "normal" weather this month with periodic shots of cooler and warmer weather. Cold isn't all that exciting - let's be honest. The bigger question for me is whether we can squeeze out any snowflakes with this pattern. At this point it isn't looking good. 

As the cold comes down there's an offshore low will likely wind up and track near New England. It seems likely that it will impact us with any snow though it's not out of the realm of possibility. There's also a chance cold air overhead could lead to some scattered rain or snow showers has the disturbance moves overhead. 

Check out the European Ensembles for the next 15 days. The Euro has 12 of 51 members showing measurable snow with only 2 of 51 showing more than 2" of accumulation. So yeah there's a chance but don't wax your skis yet.

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<![CDATA[After a Record Warm October - How's November Look?]]>454817973Thu, 02 Nov 2017 20:00:42 -0400https://media.nbcconnecticut.com/images/160*123/record1.PNG

Across Connecticut this past month was the warmest October on record. In the Hartford area the average October temperature was 59.9F which beats the old record of 59.7F set back in 2007. In Bridgeport the old record of 61.4 degrees best beat by nearly a full degree with 62.3 degrees!

October was also an awfully wet month. Finally! After drought conditions started to creep back from a dry end of summer and beginning of fall we made up for that in a big way. Volunteer CoCoRaHS observers recorded more than 10" of rain in three towns - Prospect, Monroe, and North Granby. In my backyard in West Hartford we received 9.31" of rain this month!

Looking forward, we finally do see some cooler weather ahead. While the Climate Prediction Center outlook for the month shows above average temperatures being the most probable scenario it's not a particularly strong signal. In fact, we can't totally rule out a bit of minor mixed wintry precipitation next week as colder air scoots down from the north and moisture lurks nearby.

Getting anything to accumulate seems exceptionally unlikely but it is a sign of the season for sure.

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<![CDATA[Powerful Sunday Storm]]>454180903Mon, 30 Oct 2017 20:44:33 -0400https://media.nbcconnecticut.com/images/160*120/IMG_0024rh.JPG

What is it with these powerful storms during the last weekend of October? The October snowstorm of 2011, Hurricane Sandy in 2012, and now a powerful "southeaster" that knocked out power to 180,000 utility customers in Connecticut.

The storm set an October record for lowest pressure in many stations in New York State which is a testament to its strength.  Damage was widespread with uprooted trees and snapped power lines throughout New England. 

Across Connecticut the strongest winds occured in southeastern Connecticut. The WeatherFlow station on the Outer Breakwater in Stonington Harbor gusted to 73 mph. The Groton-New London Airport gusted to 67 mph and there were widespread 50-60 mph gusts across the state. 

The storm was quite remarkable on radar with a southerly low level jet of near 100 knots (115 mph) showing up over Long Island and moving north into Connecticut.

Thankfully, only a fraction of these powerful winds mixed down to the ground. Farther north, Mount Mansfield in Vermont gusted to 115 mph as the core of the low level jet crossed the mountain's more than 4,000 foot summit. Mount Washington in New Hampshire gusted to 131 mph! Out on the Cape a gust to 96 mph occurred in Mashpee and Conimicut Light in Warwick, RI gusted to 81 mph. 

Thankfully the storm's peak arrived at low tide. Believe it or not most of the coastal flooding (and it was minor) occured in the morning as residual water levels in Long Island Sound were shoved toward the coast around daybreak near high tide as the wind shifted to southwesterly. A wind gust of 40 knots in Groton corresponded with this peak in tide levels. Minor issues and flooding were reported from Old Lyme through Stonington. 

The forecast worked out quite well. We were forecasting 60-70 mph winds along the shoreline and 45-60 mph inland and most areas fell in that range. The peak of the wind occurred almost exactly when we expected between 10 p.m. to 2 a.m. as the core of the low level jet moved overhead. The question always is how much of the wind a couple thousand feet above our head will mix do the surface. Gravity waves and thunderstorms can do it and result in a particularly nasty bout of winds and another way to do it is to decrease the low level stability. We did that through most of Connecticut by increasing the temperature near the ground which promoted a bit of mixing. Here's a look at Hartford which managed to gust to 44 mph as the temperature spiked to 70F after being in the mid 60s a few hours prior.

One of the reasons the damage was widespread was the incredible amount of rain we've seen over the last 7 days. Bristol has picked up over 10" of rain with my backyard in West Hartford receiving just shy of 10"! Heavy rain and saturated soil managed to uproot a number of trees.

The good news is our drought is gone and so are any rainfall deficits we've been dealing with this year. The weather looks quiet for the next few days which is great - the weather team could use a break :)

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<![CDATA[Destructive Winds Possible Tonight]]>453975243Sun, 29 Oct 2017 20:45:24 -0400https://media.nbcconnecticut.com/images/213*120/Wind+Gusts+Sunday+Night.png

8:30 p.m. Update: The storm is behaving as expected so far. Winds are now gusting to 37 mph in Groton and we have a handful of power outages across the state.

The key is still how much wind will be able to mix down to the surface from aloft. We have a rapidly deepening low off the coast of Delaware lifting north. You can see 3 hour pressure falls in excess fo 9mb/3hr moving north!

Aloft, our models still show an exceptionally powerful low level jet overhead around midnight. The winds about 5,000 feet above our heads will be in excess of 100 mph. While most of this will not reach the surface some of it may.

The HRRR model insists a period of destructive winds even inland. That remains a possibility though most of our models keep a narrow stable layer near the surface which will effectively prevent the strongest winds from mixing down. With the potential for convection, gravity waves, and an impinging dry slot I am concerned for gusts in excess of 60 mph statewide. Right now our forecast is for 60-70 mph gusts at the coast and 45-60 mph inland but there is a low risk for the entire state going above 60 mph. With tremendously saturated soil after recent rain a large number of uprooted trees is possible.

Earlier update: A powerful storm which may set records for sea level pressure in October across New York State is likely to produce a brief period of strong damaging wind tonight across the state. The most likely location for damaging winds is along the shoreline where it's not out of the question that winds could gust to hurricane force!!

The storm that develops will be quite intense. Most of our computer models show a storm with a pressure below 980 mb cutting to our west. This will put us on the windy side of the storm. Most of our computer models show a low level jet somewhere between 60 knots and 100 knots overhead between 10 p.m. and 2 a.m. While winds about 5,000 feet above our heads will be that of a category 2 or 3 hurricane the question is how much of that will mix down to the ground.

Generally, you need an unstable layer near the ground to mix the stronger momentum down. This sounding from the High Resolution Rapid Refresh for tonight in Groton shows the potential for 76 knots of wind (85 mph or so) to mix from that low level jet to the ground due to a shallow unstable layer near the surface (temperatures drop rapidly with height). Other models do not show this feature and keep much more of the wind bottled up above our head. Other things, however, can mix damaging winds to the surface including convection (thunderstorms) that induce vertical circulations and gravity waves which can do the same. We're forecasting wind gusts over 60 mph at the coast and at this time there is a possibility for hurricane force wind gusts around 75 mph! 

This is a classic setup for damaging wind. Something called a tropopause fold will develop right overhead. This is something we see only in the most intense storms. Effectively, the stratosphere (the layer right above the troposphere) will lower to about 8,000 feet above our heads. A dramatic increase in Ozone will occur at this height. Also, we can see a distinct warm core to this low which tends to happen only in some of the most intense Atlantic cyclones. In fact, 850mb temperatures exceed 20C off the Jersey shore!

It's really no surprise the atmospheric pressure will plummet. Here's a look at the European Ensemble forecast for this storm - notice a number of lows with pressures below 970mb! If you compare this to record low October pressures this one is outside of climatology for a good chunk of the northeastern U.S. if you exclude Sandy.

In terms of rainfall 1"-3" of rain is likely across Connecticut with some potential for heavier totals out in western Connecticut. After totals near 5" in some towns last week there may be more uprooted trees than usual given the saturated soil and weakened roots. Flooding is not expected to be a major concern. 

Be prepared to lose power and we may have issues Monday morning with downed trees and lines. Be careful driving late tonight during the brief, but wild, peak of the storm. 

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<![CDATA[Lingering Questions About Sunday's Storm]]>453493243Fri, 27 Oct 2017 08:04:19 -0400https://media.nbcconnecticut.com/images/160*120/p120i.gif

It's going to be a big storm - there's no doubt about that. The question is how bad will it be here in Connecticut as it moves north. That's an open question.

Above is the National Weather Service rainfall forecast showing a widespread 3"-4" of rain across the region. But that's by no means a sure bet. Take a look at the European Ensemble probabilities for over 2 inches of rain. With the exception of the Litchfield Hills the odds are less than 50/50. 

The amount of rain is highly dependent on the storm's track as it comes north. How far east or how far west. We just don't know yet but there is the potential for high end totals given the amount of tropical moisture involved AND the amount of lift in the atmosphere.

The second question left is the potential for strong damaging winds. We have an old fashioned Euro vs GFS battle going on here. The American model develops the storm a bit later than it's European counterpart. It's weaker and farther east. This would shift the damaging wind threat well north and east of Connecticut. The European model has the storm nearing peak intensity just west of us which would introduce the potential for 60 mph wind gusts.

In the end it's hard to know which model will be right. Both seem like reasonable solutions and both are supported to varying extents by their ensemble members. Keep in mind that this storm is the result of a complex interaction of tropical moisuture from the Caribbean and a bit jet stream distrbance diving south from Canada. There's a lot that can go wrong.

A way to visualize the possible scenarios is to look at the Euro Ensemble surface low positions late Sunday night. Each "L" represents one of 51 European model solutions with each number indicating the strength. There are some super deep and powerful storms and some that aren't all that impressive. Some storms are as far west as Pennsylvania and some storms are off the Cape! We need the model spread to shrink in order to get more specific. 

For now be prepared for damaging winds and the potential for flooding on Sunday. While both are possible they are by no means guaranteed. We've erased our yearly rainfall deficits after this week's rain so I'm OK with a more tame Sunday storm!

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<![CDATA[Growing Signals for a Powerful Weekend Storm]]>453196883Wed, 25 Oct 2017 21:58:13 -0400https://media.nbcconnecticut.com/images/160*120/GFSMA_prec_prec_102.png

All of our reliable computer model guidance shows a powerful east coast storm heading toward New England on Sunday. The devil, as always, is in the details with the exact impacts far from certain here in Connecticut.

Starting with the big picture there's a cluster of showers and thunderstorms in the western Caribbean Sea that shows some small signs of development into a tropical system. A large blob of moisture between Cuba and Mexico is going to stream north over the weekend as a powerful storm forms. Part of the uncertainty with the forecast is whether or not a tropical storm forms in the Caribbean or if it is just moisture advecting north. Regardless, a strong storm will still impact the northeastern U.S.

As the moisture lifts north there will also be a powerful coupled jet streak signature. One jet streak over Quebec and a second off the Carolinas will provide an environment that will favor strong rising motion and a strengthening storm. In essence, the right entrance region of the Canadian jet streak and the left exit region of the Mid Atlantic jet streak will line up right over southern New England. This is a strong signal for a big storm.

Not surprisingly, all of our models show a strong signal for both heavy rain and powerful winds. The GFS ensemble M-Climate rainfall forecasts (comparing this computer model to previous runs of the model) are maxed out at this lead time. That is a strong signal for flooding rain which isn't a surprise given the upper level setup and the amount of moisture coming north.

With a strong storm nearby there will be the risk for strong, damaging winds as well. Already low level wind anomalies approaching 3 standard deviations are showing up on our models.

How much wind and how much rain we get will be determined based on where the storm tracks. A rough way of looking at this is that the heaviest precipitation will likely reside west of the storm's track and the strongest winds will be east of the storm's track. A storm track over Cape Cod vs a storm track over New Jersey would make a huge difference in actual outcomes.

At this point be prepared for another round of flooding and tree damage and power outages. How bad either will be is to be determined but this one certainly bears watching.

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<![CDATA[Drought Busting Rain for Parts of the State]]>453148453Wed, 25 Oct 2017 17:41:59 -0400https://media.nbcconnecticut.com/images/213*120/COVER+PHOTO3.png

Rainfall from Tuesday night and Wednesday morning was enough to put a serious dent in the year to date deficit throughout the state.

Windsor Locks picked up 4.63" which was the biggest rainfall since Irene in 2011. The rainfall total replaced a 3.2" deficit with at 1.43" surplus from year to date. 

Bridgeport was in a 4.2" deficit however with the two day rainfall totaling 3.88" it brought that deficit to only 0.32".

The deficits will be replaced by a surplus statewide with another round of heavy rain forecasted this weekend.

For more on the weekend wind and rain threat click here.

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<![CDATA[More Rain Coming After a Month-Worth of Rain in 2 Days]]>452857493Wed, 25 Oct 2017 10:20:50 -0400https://media.nbcconnecticut.com/images/213*120/Barnum+Avenue+Between+Kent+and+Sage1.jpg

Parts of Connecticut received a months worth of rain over two days and more periods of rain are likely today, with scattered showers tonight and a chance for more showers tomorrow. 

On Sunday, showers and thunderstorms are in the forecast with heavy rain Sunday and Sunday night before diminishing on Monday.

The highest rainfall totals from the storm from Tuesday night into Wednesday morning were in eastern Fairfield and western New Haven counties. 

The highest rainfall total recorded was in Ansonia with just under 5 inches of rain. 

Seymour is dealing with leaves down and minor flooding Wednesday morning and police are asking people who live and work in town to be cautious during the morning commute.

The high rainfall totals led to flash flooding throughout the state. Take a look at the situation late Tuesday night on the Bridgeport/Stratford line. 

In addition to the heavy rain the other significant factor with the storm system was damaging winds.

Winds gusted over 40 miles per hour in parts of the state, which led to thousands of power outages on Tuesday. 

A tree came down onto power lines on Mattabassett Street in Bristol just before 4 a.m. Wednesday. In Willington, a tree came down on Cowles Road. 

Country Club Road and Miner Street in Middletown are closed after trees came down on wires.

In Madison, a tree came down on wires over railroad tracks near Scotland Road, suspending Amtrak service.

In Newington, wires came down o Maple Hill Avenue, closing the road.

Eversource reported 4,300 outages throughout the state as of midnight, with the highest outages in eastern Connecticut, including the towns of Plainfield and Preston. Power has since been restored for thousands.

Check out interactive radar which shows scattered showers continuing throughout the state.

Photo Credit: NBC Connecticut
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<![CDATA[Big Autumn Storm Moves In]]>452616413Mon, 23 Oct 2017 21:39:01 -0400https://media.nbcconnecticut.com/images/213*120/DM1PwrqX0AA_8-w.jpg

Powerful winds, flash flooding and even severe thunderstorms. There's a lot to talk about with the Tuesday storm. Let's start with the rain.

Flash flooding is a possibility in some areas with locally heavy rain totals expected. On average 1.5"-3.0" of rain is forecast but I would not be surprised to see a localized pocket of as much as 5" of rain! The most likely location for this is in western Connecticut in a handful of towns. Our high resolution models show the potential for some big totals including the RPM (pictured below) which prints out nearly 6" of rain parts of the Litchfield Hills.

The good news is our recent stretch of dry weather will mitigate the river flood threat. Smaller rivers and streams may see flooding but the bigger rivers such as the Farmington, Housatonic and Connecticut will stay in their banks.

While scattered showers and thunderstorms are possible through the day on Tuesday the heaviest rain will be centered on Tuesday evening and overnight.

The other issue tomorrow will be strong and damaging winds. Something called a low level jet will develop across Connecticut during the day tomorrow. This occurs often. The question is how much of the strong winds in the low level jet will mix down to the ground. Hurricane force winds 3,000 feet above our heads can exist with barely a puff of wind at the ground! In this case there seems to be a bit more mixing than we typically see in these events which should promote strong and gusty winds across the state. Our forecast is for 45 to 60 mph wind gusts peaking Tuesday evening and night.

The other thing we'll have to watch tomorrow is the possibility for severe thunderstorms. This is a setup known as a low CAPE/high shear setup. While these don't always produce with such strong low level shear any thunderstorm that does develop need to be watched closely. Damaging winds and an isolated tornado are possible. 

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<![CDATA[Heavy Rain & Damaging Wind Possible]]>452357053Mon, 23 Oct 2017 11:23:48 -0400https://media.nbcconnecticut.com/images/160*120/NAMMA_925_spd_060.png

Quite an autumn storm is moving toward Connecticut and we're becoming more confident in a period of strong, damaging winds along with heavy rain. The worst of the storm will be Tuesday evening through Wednesday morning. Possible impacts from the storm include:

  • Strong, damaging winds of 50-60 mph in some towns.
  • Scattered power outages and downed trees.
  • Heavy rain and localized urban flooding.

The wind will begin to pick up Tuesday morning across Connecticut with a stead increase through the day and into the evening. The reason for the wind will be a strong pressure gradient between an area of high pressure over the Atlantic Ocean and an area of low pressure over the Great Lakes. 

With that pressure difference the winds will really roar above our heads Tuesday evening and Tuesday night. Winds will reach well over 60 mph about 2,000 feet above the ground out of the south. 

The question is how much of that wind will mix down to the ground and how much will remain bottled up just above our heads. It all comes down to how stable (or unstable) the atmosphere is. Typically, a shallow layer of stable air near the ground protects us from the powerful winds above our heads. Another factor can be whether or not thunderstorms can create vertical circulations (updrafts & downdrafts) that are able to transport stronger winds from aloft to the ground. What is somewhat unique Tuesday PM/Wednesday AM is that there is not much stability near the ground AND there's a bit of instability aloft which may promote thunderstorm development. Both of those factors make us concerned about damaging winds.

Besides strong gusty winds from Tuesday evening through Wednesday morning there may be enough instability to trigger a severe thunderstorm or two. We will have to watch the radar very closely. While not likely there will be sufficient wind shear for tornadoes to develop. With most trees still covered in leaves the threat for tree damage is a bit higher than it would typically be this time of year.

The other issue with this storm will be heavy rain. Plenty of moisture and a slow moving cold front will result in several periods of torrential downpours. Flood issues should remain relatively minor given our recent spell of dry weather, however a few pockets of urban street flooding are certainly possible.

We'll keep you posted on the storm as it draws closer!

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<![CDATA[Warm Weekend and an Unsettled Week Ahead]]>451985653Fri, 20 Oct 2017 21:35:23 -0400https://media.nbcconnecticut.com/images/213*120/Evening_forecast_on_October20th2017_1200x675_1078177859921.jpg

Another incredibly warm weekend is ahead of us with temperatures making a run at 80 degrees Saturday. The record for the day is 82F set back in 1920. Already this fall has been the warmest on record (9/1-10/20) and we'll tack on a bit more to those big anomalies by Sunday. 

Beyond the weekend's warmth my attention is shifting to a storm moving in on Tuesday. A deep trough of low pressure and a connection of tropical moisture will allow a strong storm to develop. With a strong area of high pressure to our east and the low to the west the wind will roar later Tuesday. This sounding from the GFS computer model shows winds of hurricane force only 2,000 feet above the ground! While not all of this will reach the ground strong wind gusts are certainly a possibility.

Additionally, unusually warm water temperatures will help keep the atmosphere a bit more mixed than we typically see in these southerly flow setups. A lot of times in fall and winter cold water temperatures lead to a shallow layer of stability that prevents stronger wind from mixing down to the ground.

The extent of the damaging wind threat is still unclear. How strong the storm is, and where it tracks, will determine how strong the winds will get. The other wild card is whether enough instability develops for thunderstorms to form. We'll be watching this closely!

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<![CDATA[Record Warm Fall]]>451532653Wed, 18 Oct 2017 21:46:39 -0400https://media.nbcconnecticut.com/images/213*120/Evening_Forecast_for_October_18_1200x675_1076255811713.jpg

Meteorological fall is defined as September, October, and November and this is the warmest start to fall we've seen on record. More than 47 days in we're absolutely roasting. 

Of the last 113 starts to fall this fall has been the warmest. The mean temperature in the Hartford area season-to-date is 65.4 degrees. According to the Southeast Regional Climate Center a temperature like this in fall is more typical of Roanoke, VA than Hartford, CT. 

In New Haven the average temperature this season is 66.4 degrees of 4.3 degrees above normal. This would equate to what a fall is typically like in Philadelphia, PA.

It's no surprise with temperatures this warm our fall foliage is behind schedule. Leaves change color as chlorophyll breaks downs allowing a leaf's yellow and orange pigment to become dominant.  Typically, the fall colors occur around the same time every year as the biggest factor in chlorophyll breakdown is the shortening days and longer nights. 

This year, however, it's been so warm the chlorophyll is breaking down slower than usual in most trees according to UConn Extension Forester Thomas Worthley. He also points out foliar fungi on sugar maples following a wet summer have sent those trees into early dormancy. 

Even across Vermont, New Hampshire and Maine fall colors are way behind schedule. This satellite image from GOES-16 shows hues of orange and red in the mountains of northern New England. Here in southern New England (outside of the Berkshires) things remain quite green. That said, we're expecting vibrant colors to pop in about a week which is a remarkable two weeks behind schedule in the Northwest Hills. Peak color in the Hartford area likely won't be until just before Halloween. 

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<![CDATA[First Frosts are Getting Later and Later]]>451353623Tue, 17 Oct 2017 20:06:14 -0400https://media.nbcconnecticut.com/images/160*120/DMVmrzgVQAEgfZr.jpg

The growing season is getting longer and longer and our first freeze is occuring later and later in fall. While this may be good news for your backyard garden it's yet another local symptom of climate change. 

The numbers are quite striking. Since 1970 Climate Central found that the average first freeze (32 degrees) in Hartford is occuring nearly 12 days later now than it did 47 years ago. The meticulously maintained weather records in Norfolk at the Great Mountain Forest show a similarly disturbing trend. 

Since records began in 1943 the average first freeze has moved from September 26 to October 15! That is 19 days based on a linear regression analysis. The average last freeze in spring has also gotten earlier and earlier as the earth has warmed.

The Environmental Protection Agency found that the growing season across the contiguous 48 states as increased by 2 weeks on average. There are both good and bad things that can come from a longer growing season according to the EPA.

Changes in the length of the growing season can have both positive and negative effects on the yield and prices of particular crops. Overall, warming is expected to have negative effects on yields of major crops, but crops in some individual locations may benefit.1 A longer growing season could allow farmers to diversify crops or have multiple harvests from the same plot. However, it could also limit the types of crops grown, encourage invasive species or weed growth, or increase demand for irrigation. A longer growing season could also disrupt the function and structure of a region’s ecosystems and could, for example, alter the range and types of animal species in the area.

So when is the average first freeze of the year? Based on the 1981-2010 normals the average first freeze at Hartford Bradley International Airport is on October 13 and at Bridgeport Sikorsky Airport November 3. 

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<![CDATA[Ophelia Strikes Ireland]]>451184873Mon, 16 Oct 2017 21:51:45 -0400https://media.nbcconnecticut.com/images/218*120/DMRBfcMXcAMubgX.jpg

After a wind gust to 118 mph in County Cork parts of the Irish countryside are littered with debris following Storm Ophelia. The storm was a remarkable one.

Hurricane Ophelia strengthened to a category 3 hurricane near the Azores and was a hurricane as late as 11 p.m. Sunday night just hours before striking Ireland. With the exception of Hurricane Debbie (1961) this is the farthest northeast a hurricane has been observed in the Atlantic Ocean.

The cold water around Ireland is not hospitable to hurricanes, however. Ophelia lost its tropical characteristics as expected before making landfall on the Dingle Peninsula early Monday. While the storm was no longer a hurricane - much like Sandy - it didn't weaken. In fact, Ophelia strengthened as it continued to get its energy from the a powerful jet stream over the North Atlantic. 

Ireland is no stranger to powerful Autumn and winter storms though Ophelia was one of the stronger ones in recent years. 400,000 utility customers lost power from the storm and there was quite a bit of structural damage in Counties Cork and Kerry. Storm surge flooding was quite widespread in some areas on the southern and western coasts of of Ireland - including Galway.

One incredible side effect of Ophelia was the storm's wind managed to fan wildfires in Portugal and the storm's circulation sucked the smoke north into the United Kingdom. In London, the afternoon sky turned a creepy orange/red thanks to Ophelia and the horrific wildfires Ophelia helped fan on the Iberian Peninsula. 

A remarkable storm during a remarkable hurricane season. 

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<![CDATA[Weekend Outlook]]>450696163Thu, 12 Oct 2017 21:17:24 -0400https://media.nbcconnecticut.com/images/213*120/Nightly_Weather_Forecast_for_October_12_1200x675_1072229443764.jpg

It's a tough forecast for the weekend with a few chances for showers both Saturday and Sunday. What is clear is that warmer air will move in - in fact temperatures on Sunday may come close to 80F in a few towns. 

Typically, as warm air moves in air is forced to rise. This results in clouds and sometimes precipitation. What we're trying to figure out now is whether or not we'll see any rainfall this weekend as warmer air (and moisture) streams in from the Mid Atlantic. 

Right now it appears that a sprinkle or two is possible Saturday and a few showers are possible Sunday morning. A cold front sweeps in Sunday night and a period of lovely October-like weather moves in for early next week. 

By the end of the 10 day forecast there is a signal for warmer air buidling back in with a large ridge of high pressure. Record warmth is possible in parts of New England, the Great Lakes, and southeastern Canadaby the weekend of October 21-22. 

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<![CDATA[Incredibly Beautiful Clouds]]>448570433Fri, 29 Sep 2017 11:22:51 -0400https://media.nbcconnecticut.com/images/246*120/22135701_10159362460305162_1588521342200052701_o1.jpg

If you didn't look up this afternoon or this evening you missed out on an atmospheric treat. A gorgeous batch of cirrocumulus clouds spread across the sky resulting in an epic sunset across the state. But that wasn't all!

Cirrocumulus clouds are made up of both ice crystals and supercooled water droplets. These clouds were likely more than 25,000 feet above our heads! In this case a "hole punch" or "fallstreak hole" developed over some towns this afternoon. Nora Dudchik took this incredible picture at the parking lot of Hilltop Barbeque in Moodus. 

A fallstreak hole forms as ice crystals begin to grow rapidly through deposition (see the streaks) and the supercooled water surrounding the ice crystals begins to evaporate. Essentially, the ice crystal grows at the expense of liquid water. This change in phase exists because the atmosphere is subsaturated with respect to liquid but supersaturated with respect to ice. A hole in the cirrocumulus cloud with streaks of ice crystals (snow) falling out of it is the result. A fallstreak or hole punch cloud!

The cool clouds had a neat look from above on our new GOES-16 satellite but an even neater look from below.

If the cirrocumulus wasn't beautiful enough we also had some irridescence that occured as sunlight passed tiny ice crystals or water droplets in the clouds. The ice crystals or droplets diffract the sunlight resulting in what appears to be a rainbow in the cloud. Cool stuff, right? 

Even when the weather is a bit boring (for us meteorologists!) there is almost always something to marvel at :) 

Photo Credit: Keith Urbowicz / Old Lyme
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<![CDATA[Cooler Temperatures (For Now)]]>448093413Tue, 26 Sep 2017 21:39:36 -0400https://media.nbcconnecticut.com/images/213*120/DKsYATpX0AYo2cK.jpg

For a few days we've been looking ahead to a temperature drop this weekend. On Saturday we're forecasting a high of 64 degrees which isn't exactly unusual for the time of year but will come as a bit of a shock after the last month. There are signs, however, that our cool down will be somewhat short lived.

In about a week another surge of warmth will overspread a good chunk of the eastern U.S. and Canada. Above you can see the day 6-day 11 temperature anomalies across North America. A deep trough of low pressure over the Pacific Northwest will force the jet stream north into Canada flooding us with more warmth. Another period of record warmth is possible for Columbus Day weekend.

Otherwise the weather pattern looks awfully quiet. A few showers are possible pre-dawn Thursday with some moisture streaming north (indirectly from Maria) and another period of showers on Saturday. Don't get too excited - most towns will struggle to see more than a tenth of an inch.

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<![CDATA[Another Scorcher but Where's the Rain?]]>447809433Mon, 25 Sep 2017 21:02:30 -0400https://media.nbcconnecticut.com/images/213*120/DKnBVyTXUAEiVk4.jpg

92 degrees on Sunday and 91 degrees on Monday. This is hot stuff. Getting above 90 degrees this time of year is a challenge given the low sun angle and shorter days but we managed to do it 2 days in a row. The only other time that has happened was exactly a decade ago - September 25th and 26th, 2007. 

After this stretch of record warmth we will see a gradual temperature drop. By the weekend high temperatures will struggle out of the 60s with a chance for some rain - especially Saturday morning. 

The weather pattern looks pretty quiet going forward but we do need some rain. Here in West Hartford we've only picked up 1.61" of rain for the month of September. In Windsor Locks 2.19" has been recorded. The 6-10 day forecast has a high probability of below normal precipitation. 

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<![CDATA[Watching Maria]]>446977203Fri, 22 Sep 2017 21:56:28 -0400https://media.nbcconnecticut.com/images/160*120/gefs_AL15_2017092218.png

Finally, Jose is drifting away and falling apart in the Atlantic Ocean. Good riddance. Our attention now is on Hurricane Maria which is north of the Turks and Caicos and heading north. 

There is some risk to North Carolina from Maria. Another blocking ridge of high pressure in the Atlantic will, at least initially, prevent the hurricane from rocketing into the North Atlantic. The Euro and GFS ensembles show some risk for the Mid Atlantic and especially the Outer Banks as Maria interacts with an upper level low over the southeastern U.S. which essentially tugs it west a bit.

Locally, we have two possible impacts from Maria we'll be watching. One, is that the storm could meander near the Outer Banks before racing out to sea and some moisture gets transported north resulting in a period of rain Wednesday and Thursday. That's a distinct possibility and currently reflected in our forecast. 

A second, and much less likely scenario, is that Maria moves much farther west over North Carolina than currently suggested and the storm races northeast and impacts us with some wind and rain (as a much weakened storm). 

There is virtually no chance of a direct or serious tropical storm impact here for a couple reasons. One, is a weakness in the blocking ridge east of us due to Jose and the second is a digging trough coming in from the west that will kick Maria out to sea.

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<![CDATA[Remembering the Hurricane of 1938]]>224328591Fri, 21 Sep 2018 09:03:41 -0400https://media.nbcconnecticut.com/images/213*120/hurricane+of+1938.jpg

NOTE: This article was first published in 2013

On September 21, 1938 one of the most violent storms to impact New England since colonial times raced ashore near New Haven and spread a deadly combination of wind, rain and storm surge from Long Island to Quebec.

This was the only category 3 hurricane to strike Connecticut in recorded history. Sustained wind speeds reached 115 mph in parts of New London County, and wind gusts over 100 mph were common across the rest of the state. Five-to-ten inches of rain sent rivers flooding over their banks and weakened the roots of trees that were uprooted by the millions across New England.

Wilbur Beckwith was in 4th grade in Niantic when the infamous hurricane of '38 struck without warning. The wind was blowing open the windows in his classroom and his teacher ordered the students to try to keep the windows closed to prevent the wind from coming in. Around 3 p.m. Beckwith walked across the street to his home just moments before the worst of the hurricane moved in.

"My sister and I were scared to death," Beckwith recalled. "One of our windows blew out and my father grabbed a hammer and nails and a card table and hammered the card table against the window."

Beckwith and his classmate Norman Peck watched out their bedroom windows to the east when parts of New London burned to the ground. The flames set the night sky aglow for miles across the Connecticut shoreline.

In Guilford, Edith Nettleton was working in the library that day. She only had one customer on September 21st, 1938. Virtually no one knew a storm was coming, including Nettleton, who came to work that morning like she did every weekday on the Guilford Green.

"It was just a normal, rainy, wind blowing day," Nettleton recalled. "The trees were beginning to go down around the green and you could see them going and it was not a pretty sight"

Nettleton, who is now 105 years old, remembers that day well. "When they eye went through some of the trees that were toppled over were blown upright and toppled the other way."

Others in Guilford remember the eye of the storm and some were caught off guard when the back side of the storm roared through.

"I well remember the lull," Martha Rebuzzini who was 13 years old at the time said, "it became quite lovely and then it started to blow again and it's true some of the trees that went one way came back another."

Rebuzzini's family hosted stranded travelers at their home since the Post Road was blocked by the East River and trees that were down seemingly everywhere.

In more rural areas it took weeks to return to normal. In North Guilford, Ruth Nettleton said her family was stranded for 2 weeks because of the trees that had to be removed from roads by axe and handsaw.

"I can just remember the trees going across the road," Nettleton said.

Many of the people who remember the '38 storm today were only kids when it struck. 8-year-old Gordy Whitman was on his brother's magazine route when the storm started raging. After the hurricane neighborhood kids started playing on the jungle of downed trees across the Guilford Green.

"We looked at all the trees on the green and one of us said to the other I bet we can go from Broad Street to Boston and back again on all the trees that have blown down without touching the ground," Whitman said. "So that was the game to see who could do it."

In Niantic Norman Peck remembers being put to work after the storm, "even though I was young I was helping drag brush on Pennsylvania Avenue."

But it was the beach communities on Long Island Sound that bore the brunt of the hurricane's fury. Many beach homes were swept into the ocean and some entire neighborhoods were demolished by the storm. Nearly 100 people died in the state many of whom drowned by a fast-moving record storm surge.

Photo Credit: Liz Kuchta]]>
<![CDATA[Watching Jose and Maria]]>445882773Tue, 19 Sep 2017 21:00:37 -0400https://media.nbcconnecticut.com/images/213*120/DKIKN4FXcAE6wH7.jpg

Hurricane Jose strengthened a bit today as it passes over the Gulf Stream. The storm, tracking about 75 miles east of where we thought it may this weekend, will result in only very limited impacts here in Connecticut. A bit of wind and rain will be about the extent of the impacts here. 

The showers should diminish later tonight and I'm expecting a mainly dry day tomorrow as the outer bands of Jose fizzle. The inner core of Jose should remain quite in fact as it wobbles southeast of Nantucket. Wind gusts of over 60 mph are still possible there. We've very lucky Jose jogged east some as the Cape and Islands would have had a really nasty storm.

While the rain ends for tomorrow the wind will actually pick up some with 30-40 mph gusts possible in some towns. Nothing too bad. 

Beyond Jose we've got a few items of note in the extended forecast. The first will be a giant ridge of high pressure that will build in from the west and allow unusually warm temperatures to develop. In the map below you can see very large temperature anomalies (>10C) as the jet stream retreats north. It's not out of the question that temperatures could approach the 90 degree mark Sunday or Monday with how warm this air mass will be. 

If we were to get to 90 it would only happen with Jose remaining far enough offshore to keep clouds away and if the wind direction cooperated (westerly winds a must). 

One wild card for next week is what will happen with Jose off of Nantucket and how Jose will interact with Hurricane Maria. For one, the giant ridge of high pressure that builds in and warms us up, will effectively block Jose from harding east into the North Atlantic. Until we figure out what Jose will do as it meanders off New England it's hard to know where Maria will track. This spaghetti plot from the European model is a pretty accurate depiction of possibilities - ranging from an east coast US threat to safely out to sea.

Maria will have to be watched and after what it's about to do to St. Croix and Puerto Rico they will certainly need a lot of our help. 

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<![CDATA[Gusty Winds, Rain in Connecticut as Jose Approaches]]>445860723Tue, 19 Sep 2017 19:13:30 -0400https://media.nbcconnecticut.com/images/214*120/NHC-NOAA.jpg

Hurricane Jose is roughly 280 miles to the south of Southern New England. Winds are currently sustained at 75 mph. 

Jose is still expected to track approximately 125 miles to the southeast of Nantucket. 

Connecticut will only experience some fringe effects, especially for the southeast corner. A tropical storm watch was issued over the weekend for southern Connecticut, but it was canceled at 11 a.m. on Tuesday. 

Winds are currently gusting over 30 mph in southern New London County. Wind gusts will gradually pick up throughout the night with gusts up to 45 mph along the southeastern Connecticut shoreline. 

Waves are becoming quite large just over the Connecticut border in Rhode Island. Waves are currently 6 to 8 feet, waves heights will increase by tomorrow morning with waves of 10 to 14 feet expected. 

Photo Credit: NHC NOAA]]>
<![CDATA[Tropical Storm Watch Canceled; Minor Impacts Still Expected]]>445522823Tue, 19 Sep 2017 16:18:23 -0400https://media.nbcconnecticut.com/images/180*120/jose091817.gif

4PM Update: Hurricane Jose is roughly 280 miles to the south of Southern New England. Winds are currently sustained at 75 mph. 

Jose is still expected to track approximately 125 miles to the southeast of Nantucket. 

Connecticut will only experience some fringe effects especially for the southeast corner. 

Winds are currently gusting over 30 mph in southern New London county. Wind gusts will gradually pick up throughout the night with gusts up to 45 mph along the southeastern Connecticut shoreline. 

Waves are becoming quite large just over the Connecticut border in Rhode Island. Waves are currently 6 to 8 feet, waves heights will increase by tomorrow morning with waves of 10 to 14 feet expected. 


Hurricane Jose is limping north, battling dry air and strong wind shear.

The National Hurricane Center dropped all Tropical Storm Watches as of 11 a.m. on Tuesday.

Hurricane Hunters flying through the storm haven't even been able to find hurricane force winds in the system. As the storm moves north, we will see some impact here locally but I'm not expecting much.

The storm will pass a bit east of where I expected it would on Sunday night. That will result in less wind and less rain than previously expected. We anticipated a minor to moderate impact locally and now we are confident in just a "minor" impact. This is why we show the "cone of uncertainty" as Jose will track on the east side of last night's cone, which was always a distinct possibility.

Rain will fall off and on Tuesday as the outer bands of Jose rotate in. Occasional squalls of wind and rain will be common throughout the day and evening. Up to 1 inch of rain is possible in most towns with a bit more in southeastern Connecticut. Winds may gust as high as 30 or 35 mph Tuesday afternoon and night. 

As the storm pulls away Wednesday rainfall will diminish but the winds will pick up. I expect the strongest winds will occur on Wednesday morning and midday as the storm pushes east. Gusts as high as 45 mph are possible in southeastern Connecticut with scattered tree and power line issues possible.

Another piece of good news is that the coastal flood threat remains quite low as winds will be mainly offshore.

While winds remain gusty on Wednesday afternoon, clouds will gradually break and much better weather will move in for the end of the week.

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<![CDATA[Tropical Storm Watches Posted Ahead of Jose]]>445182873Sun, 17 Sep 2017 20:44:44 -0400https://media.nbcconnecticut.com/images/213*120/rh091717_1200x675_1048599619905.jpg

Our computer models have wobbled west and wobbled east over the last couple days. This is to be expected. What's remained relatively consistent is our forecast of a "glancing blow" from Jose with a minor to moderate local impact. The National Hurricane Center forecast looks good to me with the storm passing about 100 miles south of Nantucket on Wednesday. 

We're right on the western fringe of this one and only a small deviation in track will make a big difference in impact. Here's what I'm thinking right now:

  • Rain begins Tuesday morning with occasional squalls Tuesday, Tuesday night and Wednesday morning.
  • Winds will increase Tuesday and peak Tuesday evening through Wednesday morning. Peak gusts in excess of 40 mph are possible from New Haven on east along the shoreline. Gusts should remain below 40 mph inland.
  • Rainfall totals of over 1 inch are possible in southeastern Connecticut. Rainfall amounts will diminish the farther north and west one goes.
  • Storm surge flooding does not look to be a big deal. A northerly wind is mainly offshore on the Connecticut coast. Minor issues at worst.
  • Isolated or sporadic tree and power issues are possible in some towns - particularly along the shoreline. 
There is still time for things to change. A track on the western side of the NHC cone would result in more significant impacts - more wind and more rain. A track on the eastern side of the NHC cone would result in less impact - with less wind and less rain. If there was a side I am currently favoring it would be the eastern or less impact side. We'll have to watch trends over the next 24 hours.

The European model (pictured above) is on the left side of the NHC forecast while the GFS is on the right side. Again, the extent of impacts is still not quite clear though at least some minor to moderate wind and rain event seems like a good bet. 

Believe it or not it's possible Jose may do a loop-de-loop southeast of New England over the next 7 days. While this is unusual it's not unprecedented. In fact, the weather pattern right now is very similar to 1961 when hurricane Esther did a loop off the Cape. Unlike Esther, Jose is a much weaker storm and impacts will be much more limited.

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<![CDATA[Hurricane Jose Path Jogs Further East]]>444742213Sat, 16 Sep 2017 17:03:44 -0400https://media.nbcconnecticut.com/images/214*120/Saturday+5+pm+national+hurricane+center+saturday.JPG

5 p.m. Saturday update: A new advisory from the National Hurricane Center moves Hurricane Jose a little further away from Connecticut.

11 a.m. Saturday Update: A new advisory from the National Hurricane Center is similar to the one at 5 a.m.

5 AM Saturday Update: A new advisory from the National Hurricane Center this morning shows little change from last night. The track of Jose keeps Connecticut in the "cone of uncertainty." The odds of Connecticut experiencing tropical storm force winds (winds sustained over 39 mph) have increased throughout the state. 

The greatest chance for tropical storm conditions is in southeastern Connecticut especially right along the shoreline from Groton to Stonington. We're continuing to look over new data and will have several updates throughout the day.


It appears we have a good 'ol fashioned American vs European model fight brewing with Hurricane Jose. The two spaghetti plots of the GFS and European ensembles are very different - the former being closer to the coast and the latter being further out to sea.

The differences in track make a huge difference in terms of what kind of impact Jose would have here in Connecticut. More often than not a blend of the two disparate model camps yields the best forecast - though it's important to not the Euro is typically the better model. With that in mind here is what I'm thinking in terms of local impact probability for Tuesday and Wednesday when Jose makes its closest pass.

A scenario painted by the GFS ensembles is possible and it would be a significant wind, rain, and coastal flooding storm. At least for now this seems like the least likely scenario. One thing that makes me think it's unlikely is the fact the jet stream pattern is generally not the pattern that fits most New England tropical storm and hurricane strikes. Generally, you want a deep trough of low pressure to capture the hurricane and slingshot it north.

A more likely scenario is more of a glancing blow with some rain and some wind but nothing that would result in more than a handful of power outages.

Still, it's important to watch the path of this storm. Sometimes the least likely scenario is the one that verifies and that scenario is still in the cone of uncertainty. What I am confident in is that even with a "direct hit" the storm will not be of hurricane strength. Cold water temperatures and slow forward motion of the storm should manage to weaken Jose relatively quickly. 

Photo Credit: NBCConnecticut.com
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<![CDATA[Jose Now a Hurricane; Connecticut Remains in Possible Path]]>444513293Fri, 15 Sep 2017 16:53:22 -0400https://media.nbcconnecticut.com/images/213*120/josefriday5p.jpg

UPDATE: Jose strengthened into a Category 1 hurricane on Friday afternoon, according to the National Hurricane Center.

Connecticut in the possible path of Hurricane Jose. The NBC Connecticut meteorologists have issued a First Alert for Tuesday and Wednesday of next week. 

Jose became a whole lot more interesting Thursday as our suite of computer models brought the storm much closer to Connecticut by Tuesday of next week.

The storm is moving west and by the weekend will begin a turn north along the east coast of the United States. What's unclear is how far west Jose will get and how strong Jose will be. The current forecast from the National Hurricane Center has Jose in a somewhat precarious position east of Norfolk, Virginia by 5 p.m. Tuesday.

Jose is essentially blocked from curving out into the Atlantic Ocean by a strong ridge of high pressure that stretches from Bermuda through the Canadian Maritimes. A blocking high to the east of New England is the single most important piece of the puzzle historically for landfalling northeast hurricanes.

The second piece of the puzzle is a trough of low pressure over the Great Lakes and Ohio River River Valley to "capture" the hurricane and pull it west while accelerating the storm north. We are missing this ingredient.

Only having one of the two ingredients likely rules out a landfalling hurricane in New England. The odds of this happening are extremely low. However, with the blocking ridge to the east Jose may be able to meander off the coast of the Mid Atlantic and bring us a period of wind and rain. 

How close to Connecticut depends on how strong the west Atlantic ridge is (stronger would push Jose farther west) and how sharp the Great Lakes ridge is (oriented southwest to northeast would prevent Jose from getting too far north). With ridges all around Jose will be trapped for a period of time with nowhere to go and may slow to a crawl. 

Where this crawl happens is uncertain. The GFS and Euro ensembles show significant spread but show about 25 percent of solutions close enough to southern New England for concern. 

This setup reminds me a bit of Hurricane Edouard in 1996 that menaced New England Labor Day weekend. The storm slowly drifted north (blocked by a strong downstream ridge) and then scooted east at the last minute.

Without the capture and acceleration north (ingredient number 2 mentioned above) - Jose is likely to weaken gradually. A direct hurricane hit remains extremely unlikely and a moderate or strong tropical storm is a reasonable worst case scenario. Some wind and some rain.

How significant the storm is locally remains quite unclear but it's certainly worth watching. 

Photo Credit: National Hurricane Center
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<![CDATA[No Way Jose]]>444318943Wed, 13 Sep 2017 21:21:39 -0400https://media.nbcconnecticut.com/images/180*120/jose0914.gif

Right off the bat I should say that the odds of Hurricane Jose impacting New England (besides big waves) are quite low. That said, our computer models today started to show a slightly more interesting evolution of the storm which will need to be watched.

The reason we're interested in Jose is what's happening across the North Atlantic. A huge, blocking ridge of high pressure will situate itself from Hudson Bay through the Davis Strait. This may be enough to prevent Jose from curving out to sea.

In fact, today's European Ensemble forecast shows 20% of modeled scenarios hooking Jose back toward the close with a slow stall or wobble off the Mid Atlantic. Note that this also means 80% still go out to sea. The GFS ensembles have 4 of 21 doing something interesting with a path into the Mid Atlantic. Again, about 20 percent.

While this is interesting that's about all we can say now. This type of path is very unusual. A few storms have stalled or drifted near the coast between North Carolina and Cape Cod - Felix in 1995 and Esther in 1961 come to mind along with, to a less extent, Edouard in 1996. Additionally, even if this were to happen the storm likely wouldn't be particularly strong and would likely be no worse than a strong fall nor'easter. 

Anytime something's lurking off North Carolina we'll have to watch it. The window for a possible impact appears to be Tuesday-Thursday of next week. 

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<![CDATA[Keeping a Close Eye on Hurricane Jose]]>443802143Mon, 11 Sep 2017 17:38:37 -0400https://media.nbcconnecticut.com/images/213*120/Cover+Photo+Jose.png

We're paying close attention to Hurricane Jose which is currently to the northeast of the Turks and Caicos Islands. 

Jose is currently a Category 2 Hurricane with sustained winds of 100 mph. 

The latest track from the National Hurricane Center has Jose circling in a complete 360 and eventually tracking toward the Bahamas and East Coast.

Meteorologist Ryan Hanrahan says anytime you have a hurricane tracking to the northeast of the Bahamas it's important to keep an eye on.

With that being said there is still a lot of spread between our computer models on where Jose will be located by the end of this coming weekend.

A few of our computer models have it making landfall in New Jersey, others have it scraping the New England coast, and many models take the storm completely out to sea.

It's something we're going to pay extra attention to throughout the week. Make sure to check back for updates on Hurricane Jose throughout the week.

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<![CDATA[Irma Jogs West]]>443343123Fri, 08 Sep 2017 23:43:59 -0400https://media.nbcconnecticut.com/images/180*120/rb_lalo-animated090817.gif

Hurricane Irma's forecast track is shifting west. This has significant consequences for both the east and west coasts of Florida. 

As of Friday evening the National Hurricane Center says Miami only has a 38% chance of seeing hurricane force winds. This means there's less than a 50/50 chance that Miami gets hurricane force winds. This is a drop from earlier. What is now better news for Miami is worse news for the Florida Keys and Southwest Florida. 

For the last 36 hours - with few exceptions - our computer models are turning Irma to the north later and later. This results in a direct impact west of Miami-Dade County close to Naples and Fort Myers, FL. 

While the wind and storm surge will be ferocious around Miami the impact appears much less than what we were thinking 24 hours ago. The impact in western Florida, however, looks much more significant. A catastrophic surge and wind event is possible near the point of landfall in southwestern Florida and on the Florida Keys. 

There are still some questions. One is how much Irma's interaction with Cuba will weaken the storm. Also what's unclear is what happens to Irma's intensity post-Cuba. Exceptionally warm water in the Florida Straits is fuel for a hurricane and there is room for additional intensification. The last question is just how far west Irma gets. It's making landfall at a somewhat oblique angle so a jog another 20 miles west will bring landfall much farther up the coast potentially putting Tampa at greater risk.

Stay safe Florida! 

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<![CDATA[Irma Looks Really Bad]]>443122143Thu, 07 Sep 2017 21:10:09 -0400https://media.nbcconnecticut.com/images/180*120/rb_lalo-animated_090717.gif

Last year I grimaced every time I heard someone talk about how devastating Hurricane Matthew would be for Florida. It didn't look great but it wasn't anywhere near a worst case scenario. Hurricane Irma, however, truly scares me. 

Irma's track is becoming a bit more clear. The storm will take a hard right turn into Florida. Yesterday there was a cluster of computer models that brought Irma east of Florida - which would have greatly reduced the impact in Miami. That eastern cluster is now gone. You can see on the European and GFS ensembles below which both agree on tracks very close to - or over - the Florida peninsula. Each line indicates a different model and the colors represent how clustered the models are (the brighter the colors the more models bring Irma over that location).

This represents a pretty close to worst case scenario for South Florida. A powerful category 4 hurricane emerging from the Florida Straits and putting Miami-Dade and Broward Counties on the most dangerous right hand side of the storm is currently forecast. The left side, not quite as strong, would still produce widespread and serious coastal flooding on the Gulf Coast. 

What Could Change?

While it looks like Irma will be devastating there are things that could make it better. A track east or west of Florida could spare the state a direct landfall. While this seems unlikely the "cone of uncertainty" still remains very large at this juncture.

The storm's intensity is also a bit uncertain. While the most likely scenario (as currently forecast) is a category 4 hurricane there is certainly an opportunity for the storm to weaken a bit more OR strengthen more than forecast. Hurricane intensity is notoriously challenging to forecast. 

It's not a certainty this will be catastrophic but it sure doesn't look good now. 

Will it Be Worse Than Andrew?

Maybe. Maybe Not. Until we know exactly the path and intensity of Irma it's too early to draw comparisons. One thing that is clear is that Irma will be much larger in size than compact Andrew was. This could make storm surge worse and spread damaging winds across a larger area. 

Should I Be Worried About Friends and Family?

If they live in a mandatory evacuation zone they need to leave. Storm surge and flooding is what kills people during a hurricane. Outside of storm surge zones hurricanes are quite survivable - event category 5 storms.

That said, anyone in South Florida should prepare for days and days without power and be able to shelter in place for an extended period of time veen if not in an evacuation zone.

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<![CDATA[Destructive Morning Storms]]>442945213Wed, 06 Sep 2017 20:07:34 -0400https://media.nbcconnecticut.com/images/213*120/090617storm+%281%29.gif

Getting morning severe thunderstorms in southeastern Connecticut is not terribly unusual. There have been other example of storms racing north from Long Island and causing mischief in New London County and South County, Rhode Island. Today's storms were no exception. 

The storm was not preceded by an official warning for some reason but we knew these storms looked like trouble. Prior to the storm's arrival we began streaming coverage and sending out social media messages for people to watch out.

What was so concerning to us was the extreme velocities being picked up by doppler radar. A "bowing segment" was accompanied by winds over 80 mph at the bow's apex several thousand feet above the ground. In essence, the strong winds in the storm were forcing the storm to bow out or race forward.

In fact, as this storm moved over Groton it produced a 95 mph wind gust on the north crane at Electric Boat. Just nearby, you can see the incredible display on a street corner as the winds picked up, transformers blew, and trees snapped below.

The storm was a classic morning severe weather event along the shoreline. Very moist and humid air with a somewhat unstable atmosphere (CAPE values of about 1,000 j/kg indicate some instability). Above the ground very strong winds produced strong shear values which allowed storms to organize and mix some of this high momentum air to the ground. This was maximized near the bow segment's apex which tracked from Waterford into New London, Groton, and Ledyard. 

The weather balloon launch (pictured above) from Long Island shows the instability and strong winds throughout the atmosphere. The lack of a stable layer (inversion) at the surface allowed winds to mix readily to the surface.

Sadly, 1 man was killed when a tree fell on his car. This narrow band of destructive winds moved through a populated part of the state knocking down trees and wires in too many neighborhoods to count. 

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<![CDATA[Hurricane Irma - 9/1 Update]]>442520803Fri, 01 Sep 2017 21:42:46 -0400https://media.nbcconnecticut.com/images/213*120/Tropical+Track+2090117.png

Irma remains a powerful hurricane in the Atlantic Ocean this evening and there is no real change to the forecast thinking tonight.

As I talked about last night hurricanes located where Irma is now frequently curve out to sea harmlessly. About 90 percent of them do. It does look like Irma will be different. The only thing we can say right now is that Irma has an unusually high risk of impacting the United States compared to typical storms in the same spot.

The reason is a big, sprawling blocking high to the north of Irma from Bermuda stretching all the way east toward Europe. This high will effectively prevent Irma from turning north. Both the GFS and European computer models have this feature and agree a curve out to sea is unlikely in the next week.

Beyond that the forecast is very uncertain as any hurricane forecast is in the 7-10 day range. In fact a typhoon off the coast of Japan is one of the key ingredients in figuring out where the heck Irma is going.

Typhoon Sanvu is racing northeast in the open Pacific Ocean and like so many recurving typhoons it will have big impact on the downstream weather pattern. Sanvu will dramatically alter the jet stream flow over the North Pacific in the next 5 days and this will force the jet stream to buckle over North America. Everything is connected! 

Where, when, and how Typhoon Sanvu shakes up the jet stream pattern will dictate how close Irma gets to the United States and which parts of the east coast are most at risk.

The evolution of the jet stream pattern is key to figuring out whether Irma is able to scoot out to sea or if Irma is able to continue her course toward the United States. The GFS Ensembles are in remarkably good agreement for 8 or 9 days out with an east coast threat which makes sense given the setup. The European ensembles (not pictured) are more dispersed and do show a cluster of solutions that are harmlessly out to sea - let's hope this cluster is the one to verify!

Enjoy your Labor Day weekend. By Monday we'll know if this is something we should worry about or not.

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<![CDATA[Hurricane Irma]]>442423393Thu, 31 Aug 2017 21:50:09 -0400https://media.nbcconnecticut.com/images/180*120/avn_lalo-animated083117.gif

Hurricane Irma is something you're going to hear about a lot over the coming days. The category 3 hurricane near the Cabo Verde Islands is forecast to strengthen over the next 5 days. The question is where does it go after that?

This visualization from Ryan Maue shows the possible tracks of Irma quite well. One thing you'll note is that very few of the European model members take Irma out to sea. The range of possibilities stretches from Cuba all the way north to the Canadian Maritimes. Given it's current location in the Atlantic it's unusual to see a storm that's not trying to find any possible way to escape into the open ocean well east of us. 

More than 90% of hurricanes near where Irma is now do not make landfall in the United States. Generally, they have to be farther south and west. This graphic from Connecticut native, and hurricane expert, Bob Hart shows the probability of a tropical cyclone passing over the United States based on their location. This doesn't include the current weather pattern or steering currents and is only based on climatology or past storms. Irma's location is not one that's particularly favorable for a United States landfall based on past storms so why the heck are we talking about it? 

Check the forecast from the National Hurricane Center. Notice over the Labor Day weekend Irma takes an unusual path - bending to the south as it approaches the Lesser Antilles. Some storms do this but most don't. The farther south Irma gets it winds up in a more favorable position for a United States Impact. 

An additional note is how strong the hurricane is forecast to get. Right now the National Hurricane Center is forecasting a category 4 hurricane near the Lesser Antilles. This isn't a weak tropical storm we're talking about here!

Essentially a large ridge of high pressure (see the orange colors over the North Atlantic) will close the escape hatch and prevent this hurricane from doing what 9 out of 10 do - scoot harmlessly out to sea (though sometimes Bermuda gets unlucky with those "out to sea" storms). 

At least right now the weather pattern is a bit ominous for the East Coast of the United States and potentially the Gulf of Mexico as well. Nothing we can do now other than watch it. In a few days we'll know if this is something that's worth getting worried over - but for now keep calm and carry on. 

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<![CDATA[Hurricane Carol ]]>442381923Thu, 31 Aug 2017 14:14:13 -0400https://media.nbcconnecticut.com/images/200*120/DIkBBHUXcAALLNZ.jpg

Hurricane Carol was one heck of a storm. The category 3 hurricane made landfall near Groton and brought devastating flooding and wind damage to parts of southeastern Connecticut and Rhode Island (from South County to Providence). Carol is a bit forgotten – the impact was less than 1938 and it was overshadowed in the state by the remnants of Connie and Diane in 1955 that paralyzed the state with a biblical flood.

The reanalysis by Chris Landsea and the work by Jarvinen shows a landfall of Carol near Groton. This is about 20 miles east of the “Best Track” landfall location in Old Saybrook. The reanalyzed landfall location makes sense given the damage documented in Connecticut.

Carol made landfall on the morning of August 31, 1954. The storm brought category 2 force winds (sustained near/over 100 mph) in Groton and Stonington and a vicious storm surge. In New London the storm tide reached 9.6 ft MLLW, only exceeded by the 1938 storm which was 10.6 ft MLLW. The surge in New London at the tide gauge was 6.5 feet though a study by the Army Corps of high water marks after Carol revealed surges of 8-10 feet were common throughout southeastern Connecticut. In Stamford – many miles from the landfall location – the storm tide reached 10.3 ft NGVD which was only exceeded by Sandy and the 1938 hurricane.

Hurricane Carol is widely viewed to be the “most tropical” of hurricanes to hit Connecticut. What’s meant by that is that while the storm was likely going extratropical transition – Carol was the most purely tropical of the storms to strike Connecticut. Here’s one example of that – take a look at this picture taken from the old Griswold Hotel in Groton near the mouth of the Thames River.

The storm had a classic “eye” and the precipitation distribution from the storm – both east and west of the storm track – was relatively symmetrical. That’s very unusual for a landfalling New England hurricane!

In Bridgeport the monthly climate report indicates 1.62″ of rain fell on the day with a peak sustained wind out of the NNE at 40 mph with a gust to 60 mph. The report read as follows “Hurricane Carol did extensive damage to the shorelines of Connecticut. Storm center passed 50 miles east of station. Lowest pressure noted at 0920 EST, with NNE winds of 40 MPH and gusts to 60 MPH noted at 0928 EST. Airport was inundated with a maximum of 2 feet of water.” The lowest pressure reading in Bridgeport was 28.87″.

In Hartford at Brainard 2.36″ of rain fell. No wind data was recorded. In New Haven at Tweed 2.63″ of rain fell with a sustained wind of 38 mph out of the northeast. The report read “Heavy storm on the 31st. Gusts to 65 MPH 9-10 A.M. Caused heavy water manage along shore. Lowest pressure 28.77″ 9:10 A.M.”

At Windsor Locks 1.95″ of rain fell with a suatained wind of 56 mph out of the northwest! A 64 mph wind gust was recorded in the monthly report.

Cooperative observer reports for August 1954 include some interesting highlights.

  • Baltic, CT recorded 4.10″ of rain “HURRICANE” was listed in the important wx conditions space.
  • Brooklyn, CT recorded 4.00″ of rain
  • The observer in Colchester wrote a great blurb about Carol – though I can only decipher about half of it! 
  • The Danbury coop observer reported wind gusts near 60 mph
  • In Derby the coop observer reported the following “High winds on Aug. 31. Hurricane “Carol” considerable damage to trees. An additional amount of rain – 1.05″ fell from 8:30 a.m. to 12:30 p.m. on Aug 31″ That 1.05″ is in addition to the 1.56″ reported at 8:30 a.m. in Derby.
  • Even in Falls Village the observer mentioned the wind on the 31st “wind on the 31st caused considerable damage to untilities.”
  • In Groton the observer wrote “Aug 31. Winds of hurricane force from 9:00 A.M. to 11:30 A.M. did much damage to buildings, trees, and boats in this area. Power and telephone lines severely damaged causing loss of service for several hours.”
  • In Mansfield at the dam the coop observer from the Army Corps mentioned on the 31st “Note: temperature readings may be inaccurate because the box blew over during height of storm”
  • Here’s what the Middletown observer wrote:
  • Here’s the observer’s remarks in New London at Fort Trumbull.
  • In Norfolk, observer Norman Smith summarized Carol this way, “The feature of the month that was most notable was the passage on the 31st of an Atlantic hurricane. The storm here brought 2.59″ of beneficial rain with shifting gale winds from the E NE and NW. There was some damage to power and telephone lines and roads were blocked by uprooted trees and branches.”
  • In Putnam 4.25″ of rain fell and the observer noted the hurricane passed east of Putnam with considerable damage to crops and trees with some property damage.
  • In Storrs 3.35″ of rain fell. The observer wrote, “On the 31st of August Hurricane “Carol” hit eastern Connecticut hard with 60 mile wind – higher gusts – and nearly 2″ of rain between 8 and 11 a.m.
  • 4.36″ of rain fell in Westbrook – here’s the observation remarks.

The observations show a core of very heavy rain – 4″-6″ of rain near the center of the storm with less rain on the western periphery. Again this symmetry is unusual and shows that the eyewall was likely quite in tact and the storm was still quite “tropical” at the time of landfall.

Carol produced $50,000,000 in damage in 1954 dollars in Connecticut and killed 65 across New England. The storm is the only category 2 to strike Connecticut in modern times (1938 was a category 3 in Connecticut) and remains the strongest storm to strike the state in the last 59 years.

Photo Credit: Charles Orloff
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<![CDATA[Tropical Trouble]]>442307643Wed, 30 Aug 2017 21:40:20 -0400https://media.nbcconnecticut.com/images/180*120/irm0830.gif

The remnants of Harvey and newly formed Tropical Storm Irma have our attention. The peak of hurricane season is in a little less than two weeks and not surprisingly the tropics remains quite active. 

Remnants of Harvey

Harvey will likely go down as our nation's costliest natural disaster. Thankfully the rain is coming to an end in Texas and the remnants of the storm are lifting north. That will impact our holiday weekend in some way. 

A plume of tropical moisture will approach from the south and give us a rising chance for showers. Right now it appears Saturday evening, Saturday night, and Sunday will be unsettled. At this point I have scattered showers in the forecast for that window. I expect better weather to move in for Labor Day.

As Harvey's remnants move through no severe weather or flooding rain is expected.

Tropical Storm Irma

A new tropical storm in the Atlantic Ocean is on a somewhat concerning path west. Most storms at this longitude manage to find a weakness and curve out to sea but Irma may have other ideas.

Check out this "spaghetti plot" of the European computer model showing possible paths for Irma. A few things to note is that one, Irma is expected to become quite intense. And two, a number of European ensemble members bring Irma near the United States. 

Any impact is more than a week away so there's nothing to worry about now. That said, we're going to be watching it closely for you every step of the way.

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<![CDATA[A Closer Look at Hurricane Harvey]]>442060473Mon, 28 Aug 2017 20:51:19 -0400https://media.nbcconnecticut.com/images/213*120/Harvey_Death_Toll_Rises_as_Shelters_Fill_Up_in_Houston.jpg

Hurricane Harvey will go down as one of the costliest natural disasters in United States history. With destructive winds and a destructive floods this hurricane has been horrific.

How Rare is Harvey?

A category 4 hurricane landfall in the United States is unusual but certainly not unprecedented. The last was Charley in 2004. What makes Harvey so unique is the exceptional fresh water flooding in the Houston area. It appears that a large chunk of metropolitan Houston is dealing with a 1-in-1000 year flood - in other words a flood that has a 0.1% chance of occuring in any given year. 

Harvey will come close to breaking the tropical cyclone rain record for Texas of 48" set back in Amelia in 1978. What makes this so much worse is the fact this extreme rainfall is falling in one of the most densely populated areas of the country. 

How Was The Forecast?

The rainfall forecast for Harvey was phenomenal. For days prior to the flood in Houston forecasters were talking about record breaking rainfall. For several days our computer models all agreed on a huge flood threat and it most certainly verified.

The intensity forecast for wind was more problematic. The National Hurricane Center's forecast 48 hours prior to landfall was for a strong tropical storm or minimal hurricane. The storm's actual intensity at landfall was a category 4 hurricane. If the hurricane made landfall in Houston, New Orleans, Tampa, Miami, or any other large city the initial busted intensity forecast could have been disastrous. A late and panicked evacuation likely would have been deadly.

Harvey shows us how far along computer modeling and forecasting has come - with a nearly perfect rain and flood forecast several days out. Harvey also reminds us of the shortcomings in hurricane forecasting. Periods of "rapid intensification" are notoriously challenging to predict. We have much work to do!

Did Climate Change Make Harvey Worse?

Maybe. Earlier today I posted something on Facebook and Twitter about how we really don't know right now how big (or little) of an impact climate change had on Harvey. The post managed to annoy liberals and conservatives on Twitter almost immediately.

The relationship between tropical cyclones and climate change is complex and poorly understood. For one, a warmer atmosphere is able to effectively "hold" more water vapor and therefore one could argue hurricanes would be able to produce increased precipitation rates as they make landfall. Increased rainfall from tropical cyclones in a warmer world is something many climate scientists agree on. 

Professor Kerry Emanuel, a climate scientist at MIT, wrote about Harvey's exceptional rainfall today. He notes the frequently of tropical cyclone landfalls in southeast Texas, "shows no discernible trend in either the historical data or in the downscaled event. So the higher rainfall cannot be attributed to more frequent tropical cyclones."

While the frequency of tropical storms hasn't changed - temperature and steering currents have changed. Emanuel said the change in temperature (and therefore water vapor) isn't enough to explain the amount of rainfall.

As for the slow motion of the hurricane Emanuel did note a drop in the speed of modeled hurricanes over the last 7 years. Harvey's exceptionally slow movement is responsible for its extreme rainfall but Emanuel notes there is no long term signal for a drop in translational speed outside of the last few years which would indicate that climate change due to humans is not responsible.

Over the coming months and years research will be done as to what about Harvey can and can't be attributed to climate change. We know a lot about climate change but how a warming world will impact tropical cyclones in specific areas is much more uncertain.

What We Know Made Harvey Worse

Houston is the 4th largest city in the United States and has been growing at an incredible pace. The city has an elaborate system of bayous and reservoirs and it struggles to drain during most rain storms. This great piece by The Texas Tribune and ProPublica goes through some of the problems in Houston related to land use, urban srpawl, and poor urban planning. 

Could Houston Have Been Evacuated?

Probably not. And certainly not safely. The vast majority of flood deaths occur in automobiles. The last time a large scale evacuation in Houston was ordered was ahead of Hurricane Rita in 2005 and it resulted in days of gridlock. Unfortunately, the sheer number of people and the sheer size of this flood event made it impossible to mass evacuate the city. 

How To Help

NBC Connecticut is partnering with the Hartford Yard Goats to hold a Hurricane Harvey Relief Drive. Click here to learn more. 

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<![CDATA[Harvey Making Landfall]]>441785113Fri, 25 Aug 2017 20:24:01 -0400https://media.nbcconnecticut.com/images/213*120/DIHGwZEWsAA3GGh.jpg

Harvey has been a humbling storm for tropical forecasters. Just 48 hours ago the forecast from the National Hurricane Center was for a strong tropical storm or minimal hurricane to make landfall just east of Corpus Christi. Tonight it appears clear Harvey will make landfall as a category 4 hurricane. We're not that good forecasting rapid intensification of hurricanes and Harvey is another example of that.

The story tonight will be the wind and the storm surge. A deadly combination. This hurricane will likely be the first category 4 hurricane to make landfall in the United States since Hurricane Charley in 2004 and in Texas since Hurricane Carla in 1961.

If there's any positive news on a day where Harvey strengthened quickly it's that the worst of the storm will be in a fairly rural area. Not Houston, not Galveston, and not Corpus Christi. Matagorda Bay (no stranger to hurricanes - do a Google search on Indianola, Texas) will bear the brunt of the storm initally. 

Beyond tonight the story with Harvey will likely be the rain. In fact it's possible the inland rain and flooding may be more destructive and costly than the initial wind and storm surge. While the storm's intensity was not well forecast what hasn't changed over the past few days is the forecast for exceptional rainfall in Texas. Harvey is already slowing down and expected to stall near the coast. Days of rain will inundate Texas as the storm crawls along the coast.

So what are the state and national tropical cyclone rain records? 48.00" in Texas from Amelia in 1978. In Connecticut the record is 16.86" from Tropical Storm Diane (which cause the historic 1955 flood). 

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<![CDATA[Tuesday's Storms - A Close Call]]>441687943Thu, 24 Aug 2017 20:09:28 -0400https://media.nbcconnecticut.com/images/180*120/68fd8b6052e9492e91bddeaf210f21fc.jpg

We got lucky late Tuesday night. Kaitlyn and Josh were holding down the fort in the weather office until well after midnight with a very concerning weather setup. A bit of instability and a whole lot of wind shear left the atmosphere primed for an isolated tornado.

Looking back at the radar data it appears we really had some luck on our side. The setup was fairly common. A cold front sweeping in from the west, a surge of extremely humid/moist air coming in off the warm ocean waters, and a bit of instability during the overnight. What was a bit unusual was the amount of low level wind shear that was present. 

This environment reminded me a bit of the August 22 overnight tornado in Concord, MA that was exceptionally well warned by Hayden Frank at the National Weather Service in Taunton, MA. 

This sounding off the RAP models shows very modest instability but very powerful winds just off the surface. It wouldn't have taken much for some 60 mph winds to reach the surface. 

There were two radar signatures that were quite concerning. Given the low CAPE/high shear environment I wasn't surprised to see two rotating storms develop. One was in Goshen/Torrington shortly after 11 p.m. and another in Wolcott after midnight. Thankfully, no tornado touched down.

Both the Torrington and Wolcott storms had just shy of 50 knots of what we call delta-V. Basically the strongest outbound and strongest inbound velocity are added together to characterize the strength of a storm's rotation. The median value for northeastern U.S. tornadoes in a delta-V of 60 knots - with a delta-V of 50 knots immediately prior to touchdown. 

In an environment like we had Tuesday night we got lucky. One or both of those storms were candidates for brief and weak overnight tornadoes. A small increase in strength in either storm likely would have been enough to drop a tornado. 

Photo Credit: Kally Johnson
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<![CDATA[Solar Eclipse 2017 - What an Incredible Experience!]]>441577713Wed, 23 Aug 2017 22:23:29 -0400https://media.nbcconnecticut.com/images/160*120/IMG_1053.gif

At 2:46 p.m. on Monday, August 21 I saw the most incredible thing I've ever seen in my life. 

I woke up Monday morning in Mount Pleasant, SC to a thunderstorm and overcast skies. Not a great sign. All morning I obsessively checked radar, satellite, and computer model data looking for any sliver of hope that clouds would clear for the eclipse. There wasn't much to be found. 

Shortly before noon we made it to the beach in Sullivans Island, SC and skies were still overcast though beginning to brighten a bit. If we had any hope it would be right on the beach as the sea breeze moved inland and pushed showers and storms away from the coast.

By 1:30 p.m., as the eclipse began, the clouds continued to break and finally I saw some signs of improvement on the satellite loop as clouds began to break just offshore. Could we get lucky?

It's wasn't until around 2:15 p.m. the clouds thinned enough that the ongoing eclipse was even visible with our eclipse glasses. By the time of totality the clouds were so thin we got the full show. 

It's really hard to explain how incredible the experience of totality is.  In the few minutes before totality the temperature dropped rapidly. You could feel a chill with the wind accelerating down the beach. Even the darkness is odd. The light was unusually flat and on the horizon you could see brightness south, east, and north. It felt like a sunset in every direction. It is bizarre.

Pelicans and other shore birds weren't enjoying the strange midday darkness. You could hear them moving around and flying up and down the beach as totality set in. The sounds, the feeling, and the sight was an absolute shock to the senses.

After the last sliver of the sun disappeared the eclipse glasses came off and everyone stared upward. For a second I thought, "that's it?" and then it happened. A brilliant bright ring appeared surrounded by incredible darkness. The sun's corona danced and shimmered in the most breathtaking spectacle I've ever seen. It literally took my breath away. I wasn't the only person in my group on the beach to get choked up at the immense beauty and sensory overload. 

As totality ended the "diamond ring" effect caused a brilliant flash of light as the moon moved past the sun. It was beyond exhilirating. 

As a weather geek it actually could not have been any better. Throw out all the astronomical stuff for just a second! While totality occured the western horizon was covered up by a thunderstorm with a number of gorgeous cloud-to-ground flashes and rumbles of thunder. How many people have been able to see totality while a thunderstorm roared a few miles away? Not many. It was freaking awesome.

To be honest, leading up to the eclipse I thought some of the ways people describe totality were a bit over the top. Life changing? Spiritual? Emotional? After 2 1/2 minutes of totality I can say that those vivid descriptions aren't off the mark. It was one of the most magical things I've ever seen. It exceeded every expectation I had.

I'm already counting down the days to 2024.

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<![CDATA[The Great Flood of 1955]]>441056903Fri, 18 Aug 2017 21:15:34 -0400https://media.nbcconnecticut.com/images/160*131/55flood17.gif

Besides the 1938 hurricane, the 1955 flood was arguably the greatest natural disaster in Connecticut since colonial times.

The amount of rain that fell in August 1955 is so off the charts no event has come anywhere close to it in the last 100 years. That year's monthly record of 21.87″ at Bradley Airport stands alone as the wettest month on record – the second highest 16.32″ from October 2005 lags far behind.

Hurricane Connie made landfall over the Outer Banks as a minimal hurricane on August 12, 1955. The storm moved slowly up the Chesapeake Bay and dumped 5″-10″ of rain in portions of northwest Connecticut. Connie barely produced any wind in Connecticut as she passed to the west but dropped enough rain to saturate the soil and raise river levels above flood stage.

Five days after Connie, Hurricane Diane made landfall in North Carolina very close to where Connie struck. The storm moved inland and then was picked up by a strong trough diving into Michigan's Great Lakes. An exceptional band of rain setup over northwest Connecticut and western Massachusetts as the storm passed over Long Island. Having 10″-20″ of rain was common in many areas. When preceded by Connie’s 5″-10″ of rain Diane’s record 24-hour rainfall was enough to push rivers to levels that hadn’t been seen in hundreds of years.

The all-time 24-hour rain record in Connecticut occurred on August 19 in Burlington with 12.77″ falling. In Westfield, Massachusetts, an incredible 1-day total of 19.75″ fell. A close look at the 8-day rain totals from August 12, 1955 to August 20, 1955 reveal just how exceptional this flood event was.

A streamline analysis of Hurricane Diane in the August 1955 Monthly Weather Review shows a stalled out front across Connecticut between 0730 EST August 18, 1955 and 0730 EST August 19, 1955, out ahead of Diane’s circulation. For nearly 24 hours, strong convergence setup across Connecticut with deep tropical moisture advecting northward from Diane.

A preliminary report by the U.S. Weather Bureau from August 25, 1955 includes hourly rainfall totals for Bradley Field which are incredible. Here’s an excerpt from that report:

The rains in southern New England were prolonged as the storm center which was moving eastward directly along the 40º parallel for about 12 hours from 5 p.m. of the 18th to about 5 a.m. of the 19th, recurved to an east-northeast direction paralleling the southern New England coast. The hourly precipitation rates recorded at the Weather Bureay office at Bradley Field, Windsor Locks, Conn., are shown on the map. Until about 9 p.m. on the 18th, the intensities fluctuated considerably, but from then to 10 a.m. on the 19th the rate was quite constant, averaging nearly .6 inch per hour for 15 hours. The greatest amount from this record in a 24-hour period, 12.05 inches, is from 10 a.m. August 18 to 9 a.m. August 19. This compared with the previous maximum 24-hour rainfall of record at Hartford, Conn., of 6.82 inches occurring on July 13, 1897.

The 1955 floods destroyed entire neighborhoods, entire downtowns, and entire families. Waterbury, Winsted, Naugatuck, Derby, Ansonia, Farmington, New Hartford and Putnam are just some of the towns and cities that were changed forever.

With the amount of rain that fell it’s not surprising the 1955 floods set records on the Quinebaug, Farmington and Naugatuck Rivers. The Army Corps of Engineers built a monstrous system of levees and dams on those rivers to prevent a flood like the ’55 one from happening again. Barring an unforeseen catastrophic failure of the dam and levee system a flood to the level of 1955 will never happen again on those rivers.

1955 Rain Totals (From Coop Stations)

Barkhamsted – 25.06″

  • Connie – 9.11″
  • Diane – 15.95″

Burlington – 24.65″

  • Connie – 8.73″
  • Diane – 15.92″

Norfolk – 21.81″

  • Connie – 8.93″
  • Diane – 12.88″

Warren – 18.60″

  • Connie – 7.74″
  • Diane – 10.86″

Windsor Locks – 18.42″

  • Connie – 4.02″
  • Diane – 14.40″

Falls Village – 16.83″

  • Connie – 6.75″
  • Diane – 10.08″

Danbury – 14.83″

  • Connie – 8.74″
  • Diane – 6.09″

Hartford – 11.75″

  • Connie – 3.90″
  • Diane – 7.85″

Prospect – 10.96″

  • Connie – 3.41″
  • Diane – 7.55″

Middletown – 10.90″

  • Connie – 4.53″
  • Diane – 6.37″

Bridgeport – 8.34″

  • Connie – 5.32″
  • Diane – 3.02″

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<![CDATA[Friday Storms]]>440965063Thu, 17 Aug 2017 21:57:02 -0400https://media.nbcconnecticut.com/images/213*120/Model+RPM4+Precip+Cloud+CT+no+banner.png

A complex storm will approach Connecticut Friday and there is a low risk for a severe thunderstorm tomorrow. A warm front will slowly ooze across Connecticut during the day with a risk for occasional showers and thunderstorms.

  • Any thunderstorms will be isolated - not every town gets one!
  • Several rounds of showers and storms are possible during the morning, midday, and afternoon. 
  • The atmosphere will feature low instability and high wind shear. There is a conditional threat for a rotating storm that could produce a tornado or damaging winds. 

We call these setups low CAPE/high shear. Basically there isn't a whole lot of energy for storms to form but any storms that do will have enough wind shear to work with that they can rotate. Not all rotating storms produce tornadoes - far from it in fact. But as a storm begins to rotate the odds of it producing severe weather increase.

At this point we're giving this a general "low" impact for storms as anything we get would be isolated. We'll be watching it all day for you! 

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<![CDATA[Solar Eclipse Forecast]]>440849123Wed, 16 Aug 2017 23:26:06 -0400https://media.nbcconnecticut.com/images/213*120/170816_CTSolarEclipse_1200x675_1026149443805.jpg

We know at 2:45 p.m. on Monday, August 21 about 2/3 of the sun will be obscured by the moon. That's a forecast we can be 100% confident in! The question is, however, will we be able to see the eclipse? Will skies be clear or cloudy?

Here in Connecticut it looks like we're in good shape. The afternoon GFS computer model shows clear skies overhead on Monday afternoon. With high pressure overhead this seems like a reasonable solution. The European Ensemble (the European model run 50 different times with small tweaks and perturbations) shows extremely low chances for overcast skies in Connecticut.

Farther south in the path of totality the forecast is even more important. I'll be in Charleston, SC for the total eclipse and cloudy skies would really be a bummer. The current GFS forecast is just about perfect for South Carolina in August.

While this is probably too optimistic solar eclipses can help change the weather. As the amount of sunlight decreases the temperature starts to drop. As temperatures drop daytime cumulus clouds and showers that form in the heating of the day begin to dissipate. I'm crossing my fingers we wind up with a sunny afternoon but we'll see!

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<![CDATA[Hurricane Gert Will Lead to Dangerous Rip Currents at RI Beaches]]>440609293Wed, 16 Aug 2017 10:42:05 -0400https://media.nbcconnecticut.com/images/213*120/LMX___R_VO_BIG_WAVES_KNSD_130606_16F76071_1200x675_991621187914.jpg

Hurricane Gert is leading to high surf advisories and strong rip currents for coastal areas of Rhode Island, Long Island, and Cape Cod. 

Buoys off the coast of Block Island measured powerful swells of 8.5 feet this morning. 

<blockquote class="twitter-tweet" data-partner="tweetdeck"><p lang="en" dir="ltr">7 foot swells with a 12 second period at the Block Island buoy now. Those are very powerful waves thanks to Gert. <a href="https://twitter.com/hashtag/nbcct?src=hash">#nbcct</a> <a href="https://t.co/xZrCeW68KQ">pic.twitter.com/xZrCeW68KQ</a></p>&mdash; Ryan Hanrahan (@ryanhanrahan) <a href="https://twitter.com/ryanhanrahan/status/897783817951432704">August 16, 2017</a></blockquotethis morning - and still rising. These large waves and strong rip currents can be seen as close by as Misquamicut State Beach in Westerly, Rhode Island.

At Blue Shutters Beach in Charlestown, Rhode Island lifeguards closed the beach to swimming around 10 a.m. as swells began to build. 

Rip currents are currents of water that flow from the beach to the surf zone and can rapidly pull a swimmer out to sea. 

If you are ever stuck in a rip current make sure to swim parrellel to the beach until you're eventually out of the current. 

A High Surf Advisory is in effect for parts of Rhode Island and Massachusetts until 8 p.m. Wednesday. 

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<![CDATA[Hurricane Gert - Where's it Going?]]>440431653Mon, 14 Aug 2017 22:42:24 -0400https://media.nbcconnecticut.com/images/180*120/avn_lalo-animated081417.gif

Gert became the second hurricane of the 2017 Atlantic tropical season shortly before 11 p.m. on Monday. It is expected to pass well south and east of New England later this week.

While there won't be any direct impact from Gert there is the potential for powerful swells and rip currents at the ocean beaches as close as Watch Hill. 

The long period swells from Gert will move north from the storm and impact Rhode Island beaches as early as Tuesday night. Peak swell of nearly 6 feet will arrive on Wednesday. While waves of this height aren't unusual when a hurricane passes offshore Wednesday is likely to be a very busy beach day and dangerous rip currents will be widespread. This is great news for surfers but swimmers will have to be very careful on Wednesday.

Beyond Gert the tropics look like they will remain very active. A combination of factors will favor development of tropical storms and hurricanes in the Atlantic Ocean through the next 10 days. This plot from Mike Ventrice of The Weather Company shows the likely track of the next disturbance churning off the coast of Africa. This storm would have the potential to impact the Caribbean and maybe eventually the United States. It's name will likely be Henry. 

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<![CDATA[Solar Eclipse 2017 and What to Expect in Connecticut]]>440215343Mon, 21 Aug 2017 15:27:47 -0400https://media.nbcconnecticut.com/images/213*120/eclipse+lunar.jpg

On Monday, August 21 a rare total solar eclipse will be visible from coast to coast in the United States for the first time in 99 years. In fact, the total solar eclipse will be the first in the continental United States since 1979!

Here in Connecticut we will not be in the path of totality (you'll have to wait until 2079 for that) but there is still plenty to see!

What to Expect

The solar eclipse in Connecticut will start around 1:25 p.m. when a small sliver of the sun will be masked by the moon. By 2:45 p.m. about 2/3 of the sun will be obscured by the moon making which is the most we'll see. By 4:00 p.m. the solar eclipse will end. This is known as a partial solar eclipse and has occured in Connecticut most recently on December 25, 2000 and May 10, 1994.

The total solar eclipse will occur only in a narrow path from Oregon to South Carolina including Charleston, SC where I'll be for the event!

How to View

The only way to safely view a solar eclipse is through special glasses that block damaging radiation from your eyes. You can purchase these glasses at many stores including CVS, Best Buy, and Lowes. Be sure to only purchase glasses with an ISO label ensuring they're safe for using.

A pinhole or projection method can be used and is a nice idea for a project to do with kids. I remember making one of these in school to observe the 1994 eclipse in Guilford. 

Another option is shade 14 welding glasses - though these are likely to be sold out at many hardware stores.

Looking at the solar eclipse with sunglasses or the naked eye can lead to permanent eye damage or even blindness. While it is safe to take your glasses off during totality Connecticut is outside the path of totality.

What is an Eclipse Anyway?

Solar eclipses occur during a new moon when the moon's shadow is cast on earth. During a new moon the sun, moon, and earth are in line with each other. The reason there isn't a solar eclipse every new moon is because the moon's orbit around earth and the earth's orbit around the sun are not in the same plane. Only once in a while do these planes intersect and a solar eclipse occurs.

The moon's shadow is made up of a penumbra and a umbra. Only under the umbra is the moon's shadow complete resulting in a total eclipse (occasionally even with the umbra the moon is too far from earth resulting in an annular solar eclipse where a ring of the sun is still visible around the moon). In totality, a dramatic temperature drop (as much as 10 degrees) will accompany full darkness. From daylight to midnight in moments - a truly remarkable sight. Legendary WRC-TV meteorologist Bob Ryan described his first (Nantucket in 1970), and subsequent, solar eclipses in this wonderful Washington Post piece.

In the penumbra (where we'll be) part of the sun will be obscured by the moon and less solar radiation will make it to us than we typically see in the afternoon. A temperature drop (likely several degrees) will accompany this as we enter in a portion of the moon's shadow. 

How Common Are They?

Partial solar eclipses happen with a fair amount of regularity (2000 and 1994 being our most recent) while total solar eclipses are rare. The last total solar eclipse in Connecticut was in 1925 and the next isn't until 2079! 

If you're thinking there's no way you won't be around for the next total solar eclipse in Connecticut (check this calculator to see how old you'll be!) a total eclipse on April 8, 2024 will just miss us and plunge portions of Vermont and upstate New York into total darkness. We'll only be a tank of gas away from totality!

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<![CDATA[Another Round of Showers]]>439764443Fri, 11 Aug 2017 07:47:36 -0400https://media.nbcconnecticut.com/images/160*120/NAMNE_prec_prec_045.png

The forecast challenge today is once again about weekend rain. At this point it appears the best chance for rain is Saturday morning - and there are some indications a period of locally heavy rain is possible. 

How much rain is a big question. Take the Short Range Ensemble Forecast model, or SREF, for instance. It shows a range from nearly 0" of rain to 3" of rain on Saturday - the bulk of which falls in the morning. The biggest clustering of ensemble members is <0.5" of rain - so it's fair to say that while heavy rain is possible it's not the most likely outcome. A lighter rain event remains the most plausible scenario.

By Saturday midday and afternoon even though the clouds stick around we should get a period of drier weather. A renewed chance for showers develops by Saturday evening as a trough of low pressure advances in from the west.

Beyond Saturday much nicer weather moves in for Sunday and Monday. There is a low risk for showers on Tuesday with a weak wave of low pressure to our south but at this point things are looking pretty good for next week. 

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<![CDATA[Weekend Storms Bring Cooler Weather]]>438388363Thu, 03 Aug 2017 16:43:10 -0400https://media.nbcconnecticut.com/images/160*120/ECMWF_6hr1.png

Meteorologist Josh Cingranelli here guest writing for Ryan Hanrahan while he's enjoying his vacation in Italy. 

The warm air and high humidity will come to an end this weekend as a strong cold front moves through the region.

The European forecast model has the front moving through the state around 18 UTC which is equivalent to 2 p.m. 

The front will bring in showers and thunderstorms Saturday afternoon. I've been monitoring the severe weather potential over the past couple of days.

Take a look at the forecasted weather sounding for 12 UTC on Saturday for the Hartford area. 

A couple things we look at for severe weather is, CAPE (convective available potential energy) and shear. Shear is how much the wind speed and direction changes as the height from the ground into the atmosphere increases.

This sounding is displaying decent shear values but lacks CAPE. While we're still forecasting thunderstorms we don't anticipate a widespread severe weather outbreak. 

The front will bring in much drier air which will rapidly decrease humidity values. Check out the dew point values prior to the front moving in and the dew point values after the front passes. 



In addition to the drier air, an anomalous shot of cooler air will settle in for early next week. High temperatures are forecasted to be 10 to as much as 20 degrees below normal through the middle of the week.

We expect temperatures will climb back into the low 80s by the end of next week. 

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<![CDATA[Weekend Nor'Easter - Where's it Going?]]>437079723Thu, 27 Jul 2017 21:16:45 -0400https://media.nbcconnecticut.com/images/160*120/gfs_tprecip_ma_10.png

An unusual July nor'easter off the coast of the Mid Atlantic has all the makings of a gigantic weekend weather problem. The good news is - for now - the worst of this system is likely to miss Connecticut. 

The storm is very anomalous for the time of year. While nor'easters aren't unheard of in July and August it's tough to get a strong low to develop off the coast that isn't tropical in nature. What makes these storms dangerous is that with so much moisture in the atmosphere a tremendous amount of rain can fall in a short period of time.

The jet stream is going to take a big dip to the south of New England Saturday as a strong disturbance digs south. This unusual disturbance, coupled with warm ocean water, instability in the atmosphere, and oodles of moisture means a powerful storm for July will develop.

What has been so incredible about this storm is the amouint of rainfall modeled just to our south and the extreme gradient between a lot of rain and very little rain. The midday NAM solution shows approximately 8.4" of rain at John F. Kennedy Airport in Queens and 0.3" of rain in Hartford (most of which was forecast to fall tonight). 

All along we've been thinking that this storm is unlikely to come fully north into New England. One of the reasons why is that the amount of moisture and instability south of New England tends to tug these areas of low pressure south a bit. Large clusters of intense thunderstorms east of the DelMarVa penninsula can prevent moisture from streaming north into Connecticut and occasionally can be strong enough to force an area of low pressure to develop a bit farther than it ordinarily would. Especially this time of year that can be a big factor and why we haven't bitten on the really wet solutions in Connecticut.

That said, you always need to watch these things and unexpected changes can occur. Even with a storm that results in little rain in Connecticut clouds and strong gusty winds are a possibility. In fact, a Gale Watch has been issued for Long Island Sound with the potential for strong winds and rough seas.

The most likely scenario is a period of clouds, strong winds, and maybe a few showers over the shoreline. A jog to the north would mean stronger winds and heavier rain and a jog south would mean fewer clouds, less wind, and little or no in the way of showers.

We'll keep you posted!

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<![CDATA[Saturday Questions]]>436619343Tue, 25 Jul 2017 20:29:14 -0400https://media.nbcconnecticut.com/images/160*120/gfs_pr6_slp_t850_nyc_16.png

To say the Thursday night through Saturday forecast is uncertain is a bit of an understatement. The forecast from yesterday is quite a bit different today. Even with that change, the spread among our different computer models remains quite large!

One way to view the uncertainty in the forecast is to use ensembles. Basically one computer model is run 20 different times with slightly different tweaks to represent a range in plausible scenarios. When all 20 show the same thing you can assume the forecast is high confidence and when all 20 are all over the place you can assume forecast confidence is low.

So what will happen? Right now we've put a chance for showers in the forecast Thursday afternoon through Friday morning with one system moving in and then a second round of showers Saturday night. If we can time everything out we'll salvage a mainly dry Friday (day) and Saturday (day). 

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<![CDATA[Solar Eclipse: What to Expect]]>435932403Fri, 21 Jul 2017 21:34:17 -0400https://media.nbcconnecticut.com/images/240*120/usa_eclipse_map_print.jpg

One month from today the moon will pass in front of the sun resulting in an incredible display across the United States. The total solar eclipse on August 21st will be the first coast-to-coast total eclipse since 1918. 

To truly get the full experience you'll have to travel. While the sun will be approximately 70% obscured here in Connecticut totality will occur in only a narrow zone from Oregon to South Carolina. I'll be in Charleston, SC for the eclipse to experience totality and I cannot wait! If it's cloudy or rainy or otherwise overcast I will be very sad :(

The last time Connecticut experienced a total solar eclipse was January 24, 1925. The next time Connecticut will experience a total solar eclipse is May 1, 2079. They're pretty rare! The 1925 solar eclipse was viewed in totality here in Connecticut. In New York City the New York Times reported the eclipse was total above 96th street as the City was on the southern extent of the total eclipse path.

In totality the moon will complete cover the disk of the sun creating a spectacle most humans have never seen with their own eyes. The sun's atmosphere, the corona, will flash and shimmer as your surroundings plunge into darkness. The temperature drops rapidly and animals are rightfully freaked out. 

Here in Connecticut the partial eclipse will be cool to look at - but you can only do so using eye protection or some type of contraption. Read more here from NASA. I remember the May 10, 1994 partial eclipse here in Connecticut and going outside at school to watch the spectacle. 

If you can't travel to experience this total eclipse you can wait a few years and head up north. Burlington, Vermont and parts of Quebec and upstate New York will experience a total eclipse on April 8, 2024. 

Only one month to go!!

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<![CDATA[Three Tornadoes in Western New York]]>435737303Fri, 21 Jul 2017 16:40:03 -0400https://media.nbcconnecticut.com/images/160*120/tornado+1.jpg

Three tornadoes touched down in western New York this afternoon associated with a beast of a supercell that moved onshore from Lake Erie. The storm produced an EF-2 tornado that was on the ground for 5 miles in the town of Hamburg and a second EF-1 tornado on the ground for 2.5 miles in the town of Holland.

Today, the National Weather Service confirmed a third EF-1 tornado in Allegany County that was on the ground for an additional 4.2 miles.

For most of the storm's life radar detected a large amount of lofted debris as the tornado sucked all sorts of debris up in to the clouds.

This Tornado Debris Signature (TDS) was apparent for about 25 minutes as the storm traversed Erie County, NY. Unfortunately, the radar confirmation of the tornado was not relayed by the National Weather Service in warnings, statements or even in the NWS Chatroom available to the media and emergency managers.

The complex of thunderstorms responsible of the tornado and a smattering of other damage reports in New York and Pennsylvania moved south of Connecticut tonight. Behind it, quieter weather is moving in with plenty of sunshine and warm weather for Friday. High temperatures between 90 and 94 degrees will be common across the state. 

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<![CDATA[Warming Water ]]>435513083Wed, 19 Jul 2017 21:22:10 -0400https://media.nbcconnecticut.com/images/160*120/image107192017.JPG

A few hot days and the water in Long Island Sound has warmed quickly. The 3-day average water surface temperature from the Ocean Remote Sensing Group and Johns Hopkins Applied Physics Laboratory shows a pool of very warm water in the western 2/3 of the Sound.

25C water temperatures are common from Madison to Greenwich but, as usual, a pocket of much colder water (near 20C) exists around The Race and Fishers Island Sound. 

Here are two water temperature traces from New Haven Habor and New London Harbor showing the big disparity from the central Sound and the eastern Sound. You can see a definite diurnal trend in the water temperature in New Haven (warmest water during the evening and coolest around mid morning) while the New London water temperature shows no such trend. 

If you're wondering average water temperature peaks in New Haven during August while New London maxes out during the last 15 days of July and first 15 days of August at 75F and 72F, respectively.

The coldest water in summer on the east coast is in Eastport, Maine that peaks at a bone crushing maximum temperature of 51F.  

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<![CDATA[Another Heat Wave]]>435287953Tue, 18 Jul 2017 20:33:28 -0400https://media.nbcconnecticut.com/images/160*120/gfs_t2maf_slp_east2_9.png

Tuesday likely marked the first day of 2017's third heat wave. The mercury reached 90F at Bradley Airport and we're expecting several additional days at or above 90. Today also was our ninth 90 degree day of 2017. 

It's a pretty classic setup with a Bermuda High allowing warmth to move in from the west as the jet stream retreats into Canada.

It doesn't look like the warmth will stick around for too much longer as another dip in the jet stream and cooler weather moved back for the weekend. At this point a round of showers and thunderstorms appears likely for a portion of the weekend ahead of our next jet stream disturbance. Stay tuned for more specifics. 

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<![CDATA[The 1989 Tornado Outbreak]]>433637073Mon, 09 Jul 2018 20:20:48 -0400https://media.nbcconnecticut.com/images/174*120/Schohariecountyemergencymanagement1.jpg

There are only a few “classic” northeastern U.S. tornado outbreaks that jump out in your mind. The 1985 Pennsylvania outbreak is one, the 1998 Pennsylvania/New York outbreak is another, and so is the 1989 northeast outbreak. The epicenter of that outbreak was right here in Connecticut with an F4 tornado touchdown in Hamden and New Haven.

The atmosphere couldn’t have been more primed for a big tornado event. Here’s the morning weather balloon launch and sounding from Albany.

A classic elevated mixed layer with a dry adiabatic layer from 625mb through 750mb is present. What is most striking, however, is the exceptional wind shear in the atmosphere. Winds at 500mb are out of the northwest at 80 knots while in the boundary layer winds are out of the south-southeast at 10 knots! That’s about as strong as it gets.

The presence of the “EML” allowed for significant instability to develop during the heating of the day. Prior to the tornado in Connecticut temperatures reached the low and middle 80s with dew points in excess of 70F. A quick and dirty modification of that sounding for 30/22 shows just how explosively unstable the atmosphere was.

The first tornado touched down in upstate New York west of Albany and was on the ground for an incredible 42 miles. That same supercell went on to produce a series of tornadoes in Connecticut. The first tornado touched down near Route 4 in Cornwall and continued south into Bantam. The second tornado touched down in Watertown and Waterbury. The most violent of the tornadoes touched down in Hamden and continued south into New Haven.

The weather charts during the event were just incredible for a northeastern U.S. tornado outbreak with a strong disturbance moving out of southern Quebec into northern New England.

Through the day 500mb heights actually rise over southern New England with the best QG forcing displaced far to the north. Still, after the initial convective initiation in the morning those storms were able to propagate southeast into our area. The elevated mixed layer not only allowed strong instability to develop – it likely also helped keep convection relatively discrete. The atmosphere in many locations was “capped” – just enough CIN to prevent widespread convective initiation – but not capped enough to prevent all convection. The best QG forcing to the north also helped convection remain relatively scattered.

The damage in Connecticut was substantial with hundreds and hundreds of homes and businesses destroyed. Many people in the New Haven suburbs – including North Haven and North Branford were caught in the hail core of the storm with golf ball size hail or larger. Southeast of where the tornado lifted in Newhallville substantial wind damage occurred with many of the pine trees near Lake Saltonstall on the Branford/East Haven line snapped in half.

Here is some of our coverage from the 6 p.m. news on July 11, 1989.

There were other tornadoes that day – some in northern Massachusetts, others just west of Danbury in Putnam County, and another swarm in northern New Jersey. If we were able to look at radar data (which sadly, we cannot) we’d probably see a line of supercells across the region.

On a personal note, the 1989 tornado event is my first weather memory as a kid. At the time I was living in Branford but on vacation with my family on Cape Cod. When I heard about the tornado back home I was devastated! I couldn’t believe that I missed “the big one” back home. I guess I’ve been a weather weenie for 25 full years now!

Photo Credit: Schoharie County Emergency Management
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<![CDATA[Friday Soaker?]]>432763283Wed, 05 Jul 2017 19:42:07 -0400https://media.nbcconnecticut.com/images/160*120/hires_ref_nyc_43.png

Some of the pieces are coming together for a Friday morning soaker though it is by no means a certainty. A small area of low pressure called a mesolow is going to scoot toward Connecticut but it's track is still not clear. Virtually all of our computer models show this feature to various degrees around daybreak but a few miles will make a big difference between a soaker and a few showers. 

These things are fickle. Unlike a large winter nor'easter these lows are very small, can be difficult to predict, and can form with little advance notice as they're primarily driven by complex interactions with thunderstorms. For example, the mesolow could easily form 200 miles farther south in an area of deeper convection over the Gulf Stream delivering us virtually no adverse weather.

The track of the low is critical. In a very narrow area just north of the low a substantial amount of rain is possible. Along a warm front moist air from the ocean will be forced to rise rapidly resulting in heavy precipitation (very deep warm cloud depths also increase the risk for very heavy rain). This band will likely be relatively stationary and it's the kind of setup than can produce 2"-4" of rain in a short period of time. Is it over central New Jersey or is it over New Haven? I don't know. 

In addition to heavy rain there is the potential for severe weather along and just south of the warm front. Very strong shear and modest instability in the warm sector could promote severe storms. At this point that will most likely be over the Atlantic Ocean but it's awfully close to tickling the south coast and Long Island. We like to call this a "Sunrise Surprise" with these warm fronts draped along the coast. 

Stay tuned for more on this one!

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<![CDATA[Maine's Tornado Outbreak]]>432559333Tue, 04 Jul 2017 20:51:13 -0400https://media.nbcconnecticut.com/images/160*120/DDq9N0UXYAEgfPZ.jpg

It didn't feature a significant tornado but Saturday's tornado outbreak in Maine was exceptionally impressive with four separate touchdowns in a small area in the southwestern part of the state. While the "outbreak" wasn't particularly well forecast the National Weather Service in Gray, ME did an outstanding job issuing tornado warnings Saturday afternoon. 

The weather setup that developed Saturday afternoon was a classic one for tornadoes. A sufficient amount of low level moisture, locally strong wind shear in the lowest few thousand feet of the atmosphere, and adequate instability to allow storms to form all came together in a small area of northern New England. A warm front draped across central New Hampshire and southwestern Maine was sufficient to maintain supercells that occasionally produced tornadoes. 

This sounding off the HRRR shows an even more impressive environment than the SPC mesoanalysis pictured above indicates. High levels of instability and even higher values of low level shear may be more indicative of the actual environment here. 

The storms on radar were exceptionally impressive for Maine and New Hampshire. 7 tornado warnings were issued on July 1st which was the most the Gray, ME office has issued in an entire year!

The Maine tornadoes are a good reminder that ingredients for severe weather - including tornadoes - can quickly come together even when it seems unlikely 6 or 12 hours earlier. This event is a really good reminder of the importance of being aware of fast changing weather conditions. The folks at the NWS Gray office did a tremendous job maintaining situational awareness and getting the word out quickly. 

Photo Credit: Courtesy: Jackson Witherill
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<![CDATA[Remembering the 1995 Hail Storm]]>429786873Tue, 20 Jun 2017 21:38:49 -0400https://media.nbcconnecticut.com/images/165*120/1995hail31.jpg

June 20, 1995 was a sultry and oppressive day. Temperatures in the 90s down to the water with dew points in the mid 70s drove heat index values above 100º. At the same time an elevated mixed layer (EML) moved overhead creating an exceptionally unstable and volatile air mass.

This weather balloon sounding from Albany shows the EML with very steep lapse rates between 650mb and 500mb. This means that the temperature above 10,000 feet was decreasing very rapidly with height (nearly 10ºC/km). With an oppressively hot and humid airmass in place the atmosphere was primed for a big explosion.

That explosion came north of the Massachusetts border when a supercell developed and began moving south.

What was remarkable about this storm was the amount of large hail it dropped during its trek through Connecticut. Baseball-sized hail was reported in 3 towns – Vernon, Manchester, and Deep River.

The relatively isolated storm (typical of EML days) continued to move due south and produced a gorgeous looking radar image. The outflow boundary of rain cooled air surged west across Hartford and Waterbury while a backdoor cold front that started near Boston around 10 a.m. finally caught up with the storm at the mouth of the Connecticut River.

The storm was the most intense over Deep River and Lyme, possibly due to the interaction with the backdoor cold front moving from east to west. Here’s an excerpt from the National Weather Service Storm Data publication.

A cold front moving across the area generated severe thunderstorms which produced large hail and gusty winds. Baseball-size hail lasted for up to 20 minutes in Deep River causing hundreds of thousands of dollars in damage. The hailstones broke hundreds of windows in buildings and automobiles, tore holes in roofs, dented siding and automobiles, and ruined gardens. Some automobiles were totaled. In one historic building, the hail broke 25 windows, including a 100-year curved window. Thirty-two windows were smashed in an elementary school and its roof was damaged. Most of the damage was covered by insurance.

Here’s a 3-D cross section of the Deep River supercell as it crossed the Connecticut River. What is remarkable is how high the hail core of this storm was.

In fact this storm had 70 dbz radar echoes up to 30,000 feet with 60dbz up to 45,000 feet! That’s just wild. Here are some memories from people on my Facebook page.

People in Deep River still remember the hail storm vividly. Arlene Macmillan sent me these pictures of the hail (and hail damage) at her house from the 1995 storm. You can see ripped off leaves, broken shutters and windows, along the piles of hail stones. Arlene recalls the largest of the stones being billiard ball size (which is 2.25″ in diameter).

I asked Arlene a few questions about what she remembered from that day: The biggest stones were the size of billiard balls.

I got my car into the garage before the hail started. My husband was around Middletown, driving home, when he saw a black cloud over Deep River. He arrived at home less than 5 minutes after hail stopped, and saw a foot high pile of leaves covering the ground. Nothing happened to his car, not even rain. We rented out another house behind ours. $3,000 in glass damage alone at both. Sorry I don’t have a picture of our house. It was sided with weathered cedar shakes and looked as though the house had been machine gunned.

While the storm had a broad mesocyclone and was rotating during its lifetime it never produced a tornado. The rotation remained broad and aloft and never came to the surface. The closest the storm came to becoming tornadic was south of Deep River in Essex and Old Saybrook when the rotation began to lower following the interaction with the backdoor cold front.

The overall setup was not conducive to tornadoes but certainly was conducive to mega-hail, particularly where the complex interaction between the supercell and a backdoor cold front was taking place over Lyme and Deep River.

Photo Credit: Arlene Macmillan / Deep River
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<![CDATA[Severe Weather Possible Monday]]>429236483Sun, 18 Jun 2017 12:31:20 -0400https://media.nbcconnecticut.com/images/160*120/hires_ref_nyc_36.png

A round of strong thunderstorms on Monday may bring strong winds, flash flooding and even the threat of a tornado to parts of southern New England. The highest severe weather threat appears to be in western Connecticut. 

Loads of moisture coupled with the development of powerful winds (over 60 mph) several thousand feet above our heads has us concerned about the severe weather threat on Monday. This is a model sounding from the NAM model showing the potential for rotating thunderstorms given the strength of low level wind shear. The rapid increase and turning of wind with height is known as wind shear and this is a critical ingredient for tornado development. 

While only a low risk - tornadoes are possible in this kind of environment. Whether or not they form is a question and the highest threat appears as if it will set up just west of Connecticut. Any storm that starts rotating also has the potential to produce damaging straight line winds. 

The timing of storms remains a bit uncertain. The highest threat will be late afternoon and early evening as a line of thunderstorms approaches but we cannot rule out storms developing ahead of the line as early as 1 or 2 p.m. We call these discrete storms. Additionally, as the mid level winds will be out of the southwest and parallel to the front, there is the potential for very heavy rain. A flash flood threat exists in western Connecticut. 

Stay weather aware Monday! 

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<![CDATA[Rising Chance for Rain]]>428680343Thu, 15 Jun 2017 14:05:23 -0400https://media.nbcconnecticut.com/images/160*120/hires_ref_boston_29.png

Tomorrow is looking a bit damp after an awesome 2 days of weather. The timing - and amount of rain - is quite difficult to pin down. 

Warm air will stream in tomorrow above our heads and that will force air to rise resulting in clouds and even a bit of rain. You can see this by looking at the atmosphere about 5,000 feet above our heads. A southerly wind will transport warm and moist air from the ocean northward into Connecticut resulting in clouds and a rising chance for rain.

Our models are struggling with the timing of the strongest lift. Does it come in during the morning or hold off until afternoon? It's still a bit unclear. At the very least prepare for some rain tomorrow and even a few downpours. With an onshore wind temperatures will be stuck in the 60s for most of the day.

Beyond tomorrow the news is better for the weekend. As a warm front passes Connecticut we will gradually clear things out with warmer weather and even some sunshine by Father's Day. The next round of rain with a few pockets of heavy rain and storms will approach later Monday and Monday night. 

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<![CDATA[Powerful Thunderstorms Possible Tuesday]]>427996853Mon, 12 Jun 2017 14:26:01 -0400https://media.nbcconnecticut.com/images/160*120/mgWeb_WRF_20170612-150000_ANE_ECONUS_F00283000_PwinterThickness_R4km.png

The ingredients are in place for powerful thunderstorms in some towns tomorrow afternoon. An abundance of instability will fuel storms after 1 p.m. and the potential is there for severe thunderstorms as well.

One of the questions we have is how widespread will the storms be. The "forcing" in the atmosphere isn't overly strong and so it's unclear how many storms will be able to tap in to all the instability out there. With CAPE values exceeding 2,000 j/kg due in part to steep mid level lapse rates (rapid temperature drop with height 10-20,000 feet above our head) some storms may really take off.

Instability is just one piece of the puzzle. What will prevent this from becoming a more significant severe weather event is the lack of wind shear. Wind shear, or winds changing speed and direction with height, is critical for storms to organize. While supercells or powerful well-organized storm clusters are unlikely I expect we'll see a number of strong "pulse" storms that strengthen and weaken quickly. Localized downbursts and hail is possible along with an unusually large amount of lightning and very heavy rain. 

One thing to note is that with the unusually steep lapse rates and a northwest flow (offshore wind) the storms will be able to make it all the way to the beaches. This is one of those rare setups that favors Stonington Borough just as much as a town in Litchfield County. 

Be prepared for some nasty storms tomorrow. We'll have you covered all day on-air and online! 

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<![CDATA[From March-Like to August-Like]]>426891321Tue, 06 Jun 2017 22:03:00 -0400https://media.nbcconnecticut.com/images/160*120/gfs_z500a_conus_1.png

A huge pattern change is coming in the next few days and we will see about as impressive of a weather 180 as you'll ever get in New England. Today's high in Hartford was a miserable 53 degrees - making today's high the 4th coldest on record for June. 

The hideous weather pattern that we've been locked into as been due to an anomalously deep trough and upper level low that has parked itself over the northeastern United States. Unusually cold temperatures in the airmass coupled with an onshore flow off the ocean spelled disaster.

Alas, the pattern is changing in a big way. We have the potential for a 4-day heat wave beginning Sunday as an unusually warm airmass rushes in. We go from a giant trough over the northeast to a giant ridge. At least right now the wind direction appears favorable for big warmth with a general west or northwest flow over New England.

At this point we're forecasting two days in the 90s bookended by 85-90 degree heat but don't be surprised to see all these numbers go up. For the time being, even with exceptional levels of instability being modeled for Monday and Tuesday, the strong ridge of high pressure should keep us capped and hold thunderstorms at bay.

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<![CDATA[More on Wednesday's Tornado]]>426042123Fri, 02 Jun 2017 21:54:47 -0400https://media.nbcconnecticut.com/images/160*130/Webp.net-gifmaker+%281%29.gif

Wednesday's tornado warning was the first here in Connecticut in quite some time. The storm didn't produce a tornado here but did just west of here in Dutchess County, New York. Yesterday I answered a bunch of questions on the severe event but today I wanted to take a closer look at how the tornado itself formed. 

The storm produced golf ball size hail and an EF-1 tornado near Poughkeepsie. While the environment seemed fairly hostile to tornado development one managed to form anyway and radar reveals a few possible reasons why. One possible explanation is that the tornado touched down as the a line of thunderstorms moving in from the Catskills was merging with a storm out ahead of it.

Cell mergers are funny things. Sometimes as two storms interact they both manage to weaken. Other times the merger is constructive and the storm manages to increase in intensity. The Dutchess County storm was the latter. There is a marked increase in the intensity of the storm as the merger is underway. Just speculation here but the cell merger may have been able to trigger a tornado and here are possible reasons why.

  • There wasn't much low level wind shear out ahead of the line. There was deep layer shear (meaning the storms that were 40,000 feet tall were able to spin) but for tornadoes you really want strong wind shear in the lowest 10,000 feet of the atmosphere. Not all spin is created equal! As the storm interacted with the line merging from the northwest the low level wind shear may have been locally enhanced allowing a tornado to develop in an otherwise hostile environment.
  • The storm motion for a period of time was quite deviant to the right as the merger was underway and immediately after. This can also serve to increase storm relative helicity (storm relative wind shear).
  • The increase in low level shear happened in tandem with a sizable jump in the storm's updraft.

Let's dive into the radar data. The animation at the top of this post shows the storm merger occurring. Below is the radar from Long Island valid at 6:54 p.m. where you can see a sizable velocity couplet. We have a gate-to-gate shear (or delta V) of 61 knots which is higher than most tornadoes in the northeast (the median value is 45 knots). Additionally, you can see a high spectrum width (SW) overhead which indicates turbulent and chaotic flow. SW spiked at the time of the velocity couplet passing over the tornado touchdown location and immediately diminished after the tornado lifted.

The second radar grab is also around the time of tornado and it shows a spike in differential reflectivity (or ZDR) at 12,200 feet above the ground. This indicates that big liquid water drops were being lofted above the freezing level - and this occurs for only 1 scan - right during tornadogenesis. This ZDR column is a good proxy for the storm's strength and shows a notable brief jump in updraft strength.

It stands to reason that the cell merger increased low level shear AND the increase in the updraft strength that occured simultaneious was enough to result in tornadogenesis - with more efficient vortex stretching and tilting.

Even environments that wouldn't normally support a tornado can when there are complex storm interactions going on. Radar data, in retrospect, gave us a few clues as to what was going on with the storm. 

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<![CDATA[Vicious Storms: Some Answers to Your Questions]]>425707804Thu, 01 Jun 2017 11:09:03 -0400https://media.nbcconnecticut.com/images/160*120/060117tordutchess.jpeg

Wednesday evening's storms were powerful and created some incredible displays of clouds, lightning, and hail. Over the course of the evening we had tons of questions about the storms that were moving through so I wanted to take some time to answer some of them here. 

Why was there a tornado warning issued? Did a tornado touch down?

The tornado warning issued for Fairfield and Litchfield Counties last night because of strong rotation indicated on radar. The picture above shows a powerful rotating wall cloud near Poughkeepsie as the storm moved through. 

While there was strong rotation with the storm visible from the ground and on radar at least as of now there are no reports of a tornado touchdown. While there was very strong wind shear in the atmosphere - there wasn't a whole lot in the lowest 5 to 10,000 feet which is critical for tornado development. The National Weather Service in Albany is surveying damage in Wappinger's Falls, NY to see if a tornado did indeed touch down.

By the time the storm got into Connecticut the storm began to weaken substantially and as I said on air last night the tornado threat was diminishing over Sherman and New Milford.

Why was there so much hail? 

Last night's storms were prolific hail producers in some spots. Quarter size hail (or even a bit larger) in New Milford with many pea to dime size hail reports elsewhere. 

All thunderstorms contain a fair amount of ice in their clouds way above our heads. The more powerful the storm the larger this ice grows as the storm's updraft is able to keep these ice particles - also known as hail stones - suspended. As a piece of hail in the clouds (where it's below freezing) comes in contact with super cooled water it keeps growing and growing until gravity ultimately wins. These ice chunks then accelerate from the cloud down to the ground. 

Frequently, this hail melts on the way to the ground in Connecticut. Hot summer days can produce a 15,000 foot thick layer of warmth that's just too much for the hail to survive. What initially could have been a golf ball size chunk of hail in a cloud will be reduced to a mere pea size stone as it melts rapidly while falling through warmer and warmer air. Last night was a little different. 

The 32 degree wet bulb temperature was only about 8,500 feet above our heads. This means the hail only had a relatively short distance to fall to survive melting. The unusually cold environment allowed hail produced in the storm to make it to the ground more readily. 

Normally when we get thunderstorms it's warm and humid - but yesterday was sort of cool. What's the deal?

Thunderstorms thrive off instability. You want a really warm and humid air mass near the ground (think 95 degrees and sweltering humidity) and unusually cold air aloft. 

Obviously yesterday wasn't 95 and humid! What we did have yesterday was a really cold pocket of air about 18,000 feet up - which is our favorite place in the atmosphere to look. The temperature at this level approached -19C which is unusually cold. So cold in fact we didn't need big heat and humidity in  order to produce instability. It's a balance between the low level warm and upper level chill - as you want the biggest difference between the two. 

Those clouds were nuts! What were they?

The clouds we saw in many towns last night right around and just after sunset are known as shelf clouds. You get shelf clouds as cool thunderstorm outflow rushes away from a storm and forces air up on the leading edge of a storm. These shelf clouds can be beautiful - but can also be a signature that's associated with damaging winds. Thankfully, the winds in Connecticut remained below severe limits and we didn't receive any reports of wind damage.

Thank you!

On another note - a big thank you to our viewers for sending in pictures and reports all night. We really appreciate the help in these storms. You can view some of those pictures here.

Photo Credit: Emergency Response Volunteer Ryan Michaels, Dutchess County
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<![CDATA[Strong Storms Move Through Connecticut]]>425334824Thu, 01 Jun 2017 08:53:18 -0400https://media.nbcconnecticut.com/images/213*120/massive+bristol+storm+cloud.jpg


Thunderstorms are weakening across the state and though thunder, lightning, and downpours will continue until 1:30 a.m. in some areas the threat for damaging thunderstorms has passed.

The National Weather Service reports significant damage about 15 miles west of Connecticut in the town of Wappingers Falls, New York from the storm that prompted the tornado warning. An emergency manager reports a house partially collapsed and a number of trees were snapped in town. 


The thunderstorms have weakened drastically since the last update. Scattered thunderstorms and heavy rain showers continue to move east. Here's the latest timing of the showers and storms. They're moving into Windham and New London counties.



We're continuing to track a line of strong to severe thunderstorms move east across Connecticut. We have had reports of quarter sized hail in New Milford. These storms have a history of heavy rain, strong winds, and small hail.

Here's a look at the latest track:



Severe Thunderstorm Warnings continue for parts of Connecticut. Here's the latest track. These storms have a history of damaging winds, hail, heavy rain, and frequent lightning. 



The tornado warning for northern Fairfield and southern Litchfield county has expired. Severe Thunderstorm Warnings Continue for Northern Tolland, Hartford, Litchfield, and Fairfield counties. 



Tornado Warnings and Severe Thunderstorm Warnings are still in effect. 



A Tornado Warning has been issued for Litchfield and Fairfield counties.

Severe Thunderstorm Warnings have been issued for Tolland, Hartford and Litchfield counties.

The National Weather Service in Albany has issued a Tornado Warning for Southwestern Litchfield County in northern Connecticut and Southeastern Dutchess County in east central New York.

At 7:14 PM, a severe thunderstorm capable of producing a tornado was located near Hopewell Junction, or 7 miles northwest of Pawling, moving southeast at 25 mph.

HAZARD: Tornado and half dollar size hail.

SOURCE: Radar indicated rotation.

IMPACT: Flying debris will be dangerous to those caught without shelter. Mobile homes will be damaged or destroyed. Damage to roofs, windows, and vehicles will occur. Tree damage is likely.

This dangerous storm will be near Wingdale around 7:30 PM, Pawling around 7:35 PM and Gaylordsville around 7:40 PM EDT.

Other locations impacted by this tornadic thunderstorm include Stormville, Baker Corner, Beekman, South Dover, Hoxie Corner, Candlewood Trails, Clove Valley, Lower Merryall, Poughquag and Billings.


Move to a basement or an interior room on the lowest

floor of a sturdy building. Avoid windows. If you are outdoors, in a

mobile home, or in a vehicle, move to the closest substantial shelter

and protect yourself from flying debris.



A Tornado Warning has been issued for Litchfield and Fairfield counties.

Severe Thunderstorm Warnings have been issued for Tolland, Hartford and Litchfield counties. 



Storms are beginning to intensify just to our west through the Hudson River Valley. A Severe Thunderstorm Warning has been issued for Columbia, Dutchess, and Ulster county in New York. 

These storms are tracking east and we're expecting them to arrive on the CT/NY border around 6:50 p.m. 



The strongest storms continue to track to the north and west of Connecticut. We're still expecting storms to arrive in western Connecticut around 6 or 7 this evening. 

The sun is shining over a good portion of Connecticut. This is allowing for the atmosphere to become even more unstable over the state.



Storms are still on track to move into Connecticut at or after 6 p.m. A storm currently moving through the Capital region of New York is a great indication of how strong the storms can become and how unstable the atmosphere is. 

This storm moving across I-87 and through Albany is producing 60 mph wind gusts and golf ball sized hail. 



We're monitoring a cluster of storms moving towards Interstate 81 in eastern Pennsylvania. These storms will likely intensify over the next few hours prior to arriving in Connecticut.

We're still looking at thunderstorms to arrive in western Connecticut around 6 p.m.



We're continuing to monitor the severe thunderstorm threat. Storms are beginning to develop across portions of Central Pennsylvania and Upstate New York. We're forecasting the storms to move into Connecticut between 5 and 6 p.m. 

A Severe Thunderstorm Watch has been issued for Litchfield and Hartford counties. This is where the severe weather threat is the highest. This doesn't mean that other parts of Connecticut can't or won't experience severe weather it just means the threat isn't as high.


A severe thunderstorm watch has been issued until 9 p.m. for Hartford and Litchfield counties and NBC Connecticut meteorologists have issued a First Alert for potentially strong to severe thunderstorms Wednesday evening.

Storms will begin to move into western Connecticut around 6 p.m.

Some of the storm have the potential to become strong to even severe. Strong and severe storms have the capability of producing damaging winds and hail. The storms will also produce a fair amount of lightning.

Make sure to stay with the NBC Connecticut First Alert Weather Team for continuing updates on this thunderstorm threat.

Photo Credit: Gale Waldron Caruso
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<![CDATA[Wednesday Severe Weather Threat]]>425405783Tue, 30 May 2017 20:48:10 -0400https://media.nbcconnecticut.com/images/213*120/DBHWeynU0AEdoxp.jpg

Severe thunderstorms remain possible Wednesday evening across parts of Connecticut. Of course, as is almost always the case with severe thunderstorms, there are some questions that remain.

My biggest question is how much sunshine we'll see tomorrow afternoon across the state. The more sunshine the warmer temperatures will get and the more instability that will develop. As I mentioned yesterday temperatures about 20,000 feet above our heads get quite cold tomorrow evening - the question that remains is how warm and moist it will be near the surface. The warmer and moister near the ground - and the colder aloft - the stronger the instability. Instability is essential to thunderstorms.

One way to visualize the amount of instability in the atmosphere is looking at something called CAPE or Convective Available Potential Energy. Basically, the more CAPE the faster parcels of air can accelerate up. The faster that acceleration the more powerful a storm. Above is a plume diagram showing 21 different projections of CAPE from our Short Range Ensemble Forecast. If the higher CAPE values verify (which would happen with more sunshine and warmer temperatures) the bigger the storm threat we would see.

Instability is just one ingredient for a storm. Wind shear, or how winds change speed and direction with height, is another ingredient that's critical for storms. There's a boatload of wind shear around tomorrow which would allow storms to organize rapidly with a wind and hail threat as long as there's adequate instability

There is a greater than normal risk for large hail in Connecticut tomorrow given the relatively low freezing levels which will prevent hail stones from melting too much on their way down to the ground. 

A few scattered storms are possible as early as 4 p.m. in the hill towns tomorrow but more widespread activity should hold off under around and after 7 p.m. Even though the best chance of storms is across the interior - strong storms are possible across the shoreline as well.

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<![CDATA[Strong Thunderstorm Threat Wednesday]]>425185134Tue, 30 May 2017 07:36:49 -0400https://media.nbcconnecticut.com/images/213*120/Model-RPM4-Precip-Cloud-CT3.jpg

In order to get severe thunderstorms you generally need two things - instability in the atmosphere and strong wind shear. Where the two are juxtaposed there's the potential for severe thunderstorms as long as there's a mechanism for the storms to form in the first place.

Wednesday appears to be one of those times where the ingredients may overlap for a period of time. The winds near the ground will be light out of the south while the winds a couple miles above our heads will be out of the west at more than 60 mph. When winds change speed and direction with height you have wind shear. In this case we have 40 to 50 knots of wind shear between 0 and 6km up which is a sizable amount.

We also have a triggering mechanism moving into southern New England to fire storms in the first place. A cold front and upper level disturbance will swing in from the Great Lakes on Wednesday which should be enough to get showers and thunderstorms going by early afternoon to our northwest.

The question that remains, however, is how much instability will be in place. It's important to figure out how buoyant - or unstable - the atmosphere is. Generally when the air is unusually cold overhead and unusually warm and moist below you have a unstable airmass. The stronger the instability the faster air can accelerate upward resulting in strong updrafts and thunderstorms. 

We have a cold pool of air that will be moving in aloft but it's unclear how warm and moist the low levels of the atmosphere will be. This graph from the Short Range Ensemble or SREF (see below) shows a large spread in possible instability values. CAPE (Convective Available Potential Energy) ranges from several hundred j/kg to nearly 1500 j/kg. If the higher amounts of CAPE verify we could very well see some big storms Wednesday evening. If it's on the lower side of things the storms will likely struggle to maintain themselves.

Given the unusually cold mid level temperatures and strong wind shear - if the instability cooperates damaging winds and large hail would be a threat. It's still early but this is something I'm watching closely. At this point we have a threat for strong/severe thunderstorms in the forecast after 4 p.m. on Wednesday. How widepread or significant the threat is remains to be seen. 

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<![CDATA[The King Tide is Back]]>424366144Thu, 25 May 2017 13:22:33 -0400https://media.nbcconnecticut.com/images/213*120/18671655_1573861059314185_5674995177705546099_o.jpg

You may not know this but today's high tide on Long Island Sound is the highest high tide of the entire year! The moon is new (sun-earth-moon all in line) and the moon's orbit is at perigee (closest pass of the moon to earth) which makes the gravitational pull of the sun and moon on earth the strongest. The stronger that pull the higher the tides.

When the moon is at first quarter or third quarter the sun and moon are at 90 degrees. This results in lower high tides and higher low tides as the gravitational pull of the sun and earth are not working in tandem -  we call this a neap tide.

This is a graph of the high tides in New Haven from January 1 to December 31, 2017. You can see a few of them spike up - corresponding to new and full moons every month. The biggest spike is tonight at 11:45 p.m. when the astronomical tide will be 7.97 feet MLLW. Most tides are closer to 6.5 feet MLLW. 

These tide predictions are assuming there's no contribution from anything meteorological. No heavy rain flowing into rivers and streams and emptying into the Sound and no strong wind piling water into Long Island Sound. Of course there's always some impact on tides from the weather. During Hurricane Sandy Long Island Sound was nearly 10 feet above astronomical tide level due to the wind. We call that storm surge.

Thankfully the storm we're dealing with today isn't much of a storm. Winds will diminish by high tide tonight and water levels will only flood the the typically vulnerable low-lying spots right along the Sound.

Flooding from King Tides is becoming more and more common these days thanks the sea level rise. What is known as "sunny day" flooding has increased substantially over the last 10 years as ocean levels climb due to melting ice and warmer oceans. The latest research indicates more than 50% of nuisance flood days can be attributed to human caused sea level rise in New London. When these king tides occur during a storm serious coastal flooding can be the result - and with rising ocean levels more serious coastal flooding is something we will have to learn to live with.

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<![CDATA[An Unsettled Week]]>423877213Tue, 23 May 2017 13:28:43 -0400https://media.nbcconnecticut.com/images/160*120/gfs_z500_norm_conus_7.png

The weather pattern isn't great and it's a bear to forecast. The biggest item of interest on the weather map is an exceptionally deep and strong upper level low hanging out over the Deep South. This low is going to strengthen even more over the next 24 hours and will directly influence our weather.

For starters, let's talk about how unusually strong this low is for the time of year. The midday GFS computer model (above) shows 500mb heights of -5.7 standard deviations from normal over Mississippi tomorrow afternoon. Think of about as far to the left on the bell curve as you can get. You can think of how high a certain pressure level is above our heads as a proxy for how strong the low is.

Today's high clouds are a sign something is up in the atmosphere. Moisture is streaming in way above our heads associated with the big low to our south. Lots of cirrus clouds all around!

With this low to our southwest we are watching a little wave of energy that will eject northeast toward New England later tonight and tomorrow morning. Yesterday, virtually all of our computer models (with the exception of the RPM) didn't do much with this wave. Today, all of our models are trending much more impressive with the wave producing a period of clouds and rain late tonight and tomorrow morning. Figuring out the strength, timing, and track of these ejecting waves is never easy. The SREF precipitation forecast shows virtually all of the ensemble members (21 out of 21) producing rain Wednesday morning prior to noon. The midday GFS model has also jumped above the rain train and this morning we updated our forecast to include more widespread morning rain. Given ample moisture and a stronger piece of energy moving in tomorrow morning rain is a prudent forecast.

Beyond tomorrow's wet morning we'll have more rain to contend with Thursday and Friday as the entire low wobbles northeast. Rain and thunder appears likely for the end of the workweek. Hey, at least the drought is over. 

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<![CDATA[Record Warmth and Some Storms]]>423193384Fri, 19 May 2017 14:13:24 -0400https://media.nbcconnecticut.com/images/160*120/18556894_1985536368399353_2752888253459198901_o.jpg

It's not the earliest heat wave on record but it was pretty darn impressive. 94, 96, and 91 (at least) over the last 3 days makes this the first heat wave of 2017. The earliest heat wave on record occured back in 2002 when the mercury exceeded 90F for three consecutive days April 16-18.

With record warmth we managed a few loud storms last night. While the storms remained sub-severe with limited, if any, damage reports in the state they did wake many people up!

Many storms around here tend to weaken after the sun goes down. As the sun sets the atmosphere cools and instability wanes. Thunderstorms need an unstable atmosphere to form! Last night was different in that several clusters of storms actually strengthened around midnight. We actually expected this to happen as there were a few ingredients in place that were a bit unusual. The biggest was the unususally steep mid level lapse rates.

Lapse rates are easy to understand. It's simply the temperature difference between two levels of the atmosphere. We express lapse rates in degrees per kilometer - so the larger the value (or steeper the lapse rate) - the faster temperature decreases with height. This helps promote instability in the atmosphere. Last night the lapse rates were steep (in excess of 7C/km) and there was a surge in moisture a few thousand feet up after dark. The combination of increasing moisture underneath the steep mid level lapse rates helped fueld storms that lasted well into the night. 

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<![CDATA[Weekend Nor'Easter Update]]>421983763Thu, 11 May 2017 09:25:14 -0400https://media.nbcconnecticut.com/images/160*120/gfs_pr6_slp_t850_ma_13.png

The Mother's Day nor'easter is on track and we're getting more confident in some of the specifics. Yesterday on this blog I posed a couple of questions of things we still didn't know the answers to and now we can start answering them with some confidence. 

The first issue was how early will the rain begin on Saturday? We're thinking 10 a.m. to 2 p.m. for a start time across the state - and many areas on the I-91 corridor and points east will be dry until at least noon or 1 p.m. If you have stuff you need to do outside there should be a window Saturday morning where things are dry. If we're lucky we may be able to push the start off by a couple hours still! 

As for rainfall totals our 1"-2" forecast still looks good - but I do think some areas could pick up 3"+ of rain. Localized bands of heavier precipitation are a good bet. One thing that jumps out at me is the "M-Climate" or "model climate" off the GFS being maxed out. Basically, the GFS model is re-run for the last 30 years and compared to the current forecast to computer M-Climate. The amount of rain being produced in a 12-hour period Saturday night on the most recent GFS run is greater than any of those 30-years of reforecasts for this time of year! That's a good signal for locally heavy rain and possibly flooding.

As for Sunday - the forecast is still a tough one. The heavy rain will end around daybreak and we should see some light rain lingering during the morning. I do think there will be a bit of a break late morning/midday - the sun may even come out! That said, showers will likely redevelop during the afternoon as a powerful upper level disturbance swings through southern New England. 

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<![CDATA[Weekend Soaker]]>421941713Wed, 10 May 2017 21:42:33 -0400https://media.nbcconnecticut.com/images/160*120/gfs_tprecip_neng_18.png

There's a few questions we're still trying to answer regarding this weekend's nor'easter. We're quite confident in 1"-2" of rain across the state with the heaviest falling Saturday evening and night. There are a few other details we need to work on. 

1) Will we wind up seeing more than 2" of rain? Some of our computer models (namely the GFS) have been showing extremely heavy rainfall totals - some runs have had in excess of 4"! The GFS ensemble mean is between 1.5" and 2.0" and the Euro Ensemble mean is between 1.0" and 1.5" across the state. With very strong convergence, a powerful upper level jet streak and closing off low, along with an anomalous surge of moisture the ingredients are there for localized totals over 2". 

2) When does the rain begin on Saturday? Will the storm slow down just a bit on Saturday and give us a dry morning and midday? That's a possibility and could salvage people's early Saturday plans. 

3) After the rain winds down Sunday morning (it may end as early as 8 or 9 a.m.) will we see a second round of rain in the afternoon? The GFS keeps us dry while the Euro brings in a second and powerful upper level disturbance in the afternoon. If the latter solution verified a period of heavy rain and even some thunder could redevelop Sunday afternoon. I really don't have a good sense of what is going to happen here later Sunday so stay tuned for more on that. 

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<![CDATA[May Snow]]>421688113Mon, 08 May 2017 21:56:59 -0400https://media.nbcconnecticut.com/images/213*120/18359039_1556683611031930_52906596634272983_o.jpg

People in Litchfield County woke up to a bit of a surprise this morning - snow was falling at a steady clip! The official observer in Norfolk, Russell Russ, told me the snow was mixed with rain this morning from 8:00-9:00 and then at 9 a good burst of heavy snow occured. No accumulation occurred. 

This snow was nothing like what occured 40 years ago in Connecticut. The infamous May 1977 snowstorm dropped an incredible 20" of snow in Norfolk and 1.3" at Bradley International Airport. Still, in Norfolk a trace of snow has been recorded 85 times since 1943 and there have been 16 instances of measureable snow. 

The storm was a ferocious nor'easter that was almost as unsual as the October 3, 1987 storm or October 30, 2011 storm with widespread tree and power line damage due to the large number of leaves on the trees. 

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<![CDATA[Unusual Wind Storm Clobbers Vermont, New York]]>421523333Sat, 06 May 2017 08:45:03 -0400https://media.nbcconnecticut.com/images/160*120/18199542_1667501939934485_8450409264263574595_n.jpg

An unusual "gravity wave" induced wind storm produced wind gusts of hurricane force in parts of western Vermont and eastern New York Friday afternoon. The unusual wind storm occurred suddenly in the late afternoon and appears to be driven by what is known as a gravity wave.

A gravity wave is a wave (think just like the ocean) that occurs in a stable atmosphere. This vertical wave pushes the air up and down just like a ripple in a pond after you toss a rock into it. We can see this perturbation in the atmosphere by looking at the surface pressure on a barometer. These two pressure traces from Williamstown, MA and Stockbridge, MA in the Berkshires show a sharp drop and rise in the atmospheric pressure just after 4:00 p.m. This happened as the gravity wave moved over Massachusetts - the ripple overhead in the atmosphere produced a quick drop and rise in the pressure. 

North of the Berkshires - on the west side of the Green Mountains - the gravity wave was more than just a curiosity. A ferocious period of winds developed as the gravity wave moved overhead with gusts up to 74 mph in the town of Wells, VT and substantial tree damage in the cities of Rutland and Bennington, VT. 

East of Albany in the town of Brunswick, NY you can see a big pressure drop (~7mb in an hour) along with a sudden surge of winds up to 65 mph. 

The gravity wave appears to have been of a substantial enough amplitude to bring down very strong winds from aloft. The winds from 5,000 feet in the atmosphere were about 75 mph and appear to have mixed right down to the ground as this vertical wave resulted in one hell of an atmospheric ripple. The terrain absolutely played a part in this - as all of the powerful winds occurred just west of the Green Mountains (Killington, near Rutland, is ~4200 feet) and another band of strong winds occured just west of the Taconic Mountains in eastern New York. 

What triggered the gravity wave isn't clear either. Gravity waves are not uncommon - we see small ones all the time during storms but hravity waves that produce a 9mb pressure drop in an hour are very unusual and can produce really nasty winds. 

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<![CDATA[Friday Soaker]]>421214223Wed, 03 May 2017 20:26:08 -0400https://media.nbcconnecticut.com/images/160*120/gfs_pwat_conus2_9.png

A surge of tropical moisture and a deep low pressure to our west is going to bring a soaking rain into Connecticut on Friday. While the rain is expected to be heavy for a period of time we may be looking at a smidge less than we were thinking a day or two ago. 

Most of our computer models show a general 1"-2" rainfall across the state - including our high resolution models like the NAM. 

One strong signal for heavy rain is mean values of ~2" in southern Connecticut showing up on the Euro Ensembles. More than 50% of Euro Ensemble members drop over 2" of rain in the New Haven area - that's a big signal! 

At this point it appears there's a minor threat for flooding Friday afternoon. Strong lift, a good moisture plume, and even a bit of elevated instability should be enough for embedded thunderstorms and locally heavy rain. The storm is moving fast enough - and our models have cut back on precipitation totals over the last 24 hours - that we're not expecting widespread or significant flooding.

This is just another storm putting a dent in the multi-year drought we've been dealing with. It appears our fortunes have turned and we're seeing big improvement in virtually every drought indicator. 

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<![CDATA[Cut-Off Low Woes]]>420950824Mon, 01 May 2017 20:25:26 -0400https://media.nbcconnecticut.com/images/160*120/eps_z500a_noram_29.png

A dreaded cut-off low is going to pay Connecticut a visit this weekend and early next week. The result will be days and days of gloom. Cut-off lows get their name because they effectively become "cut-off" from the jet stream and they can stall out and linger for days on end. 

The pattern is a classic one for something like this to form. A dramatic block over Greenland will help force a large dip in the jet stream over New England. What doe it mean for us? An extended period of clouds, chilly temperatures, rain, and possibly even thundersytorms and small hail. 

It's tough to time out which days will be coldest or wettest or stomiest but things are not looking great for those who want sunshine. In June or July these cut-off lows are notorious for producing localized areas of excessive rainfall and even severe weather but in early May the impacts should be a bit more muted - though some heavy rain and strong thunderstorms are certainly a possibility.

Unfortunately, even after the cut-off low weakens its grip on us the day 11-day 15 period isn't looking so hot (literally) either with a cooler than normal regime over the northeastern U.S. 

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<![CDATA[Morning Thunderstorm Threat]]>420759683Fri, 28 Apr 2017 15:58:30 -0400https://media.nbcconnecticut.com/images/213*120/Model+RPM4+Precip+Cloud+Temp+CT_042817.png

With warmer air making it feel a bit like summer - we may have to deal with a few thunderstorms Saturday morning across the state. A nose of unstable air will push north in southern New England around daybreak and this may be enough to fire a cluster of strong thunderstorms in the morning.

Many of our high resolution models show a round of thunderstorms tomorrow morning and that's not surprising given the brief instability spike. The NCAR ensemble has strong odds of CAPE exceeding 1000 j/kg across Connecticut tomorrow morning which should be enough for storms.

One thing to watch is there is a fair amount of effective shear for these elevated storms tomorrow morning. While strong winds are quite likely (a shallow layer of cooler and stable air near the ground should preclude damaging wind) the combination of CAPE and shear may allow some vigorous updrafts to develop resulting in heavy rain, lightning, and even small hail.These daybreak storms aren't uncommon in these setups. Once in a while they can produce severe weather but this doesn't seem like one of those times.

As the storms move east a westerly wind develops which should allow very warm temperatures even to the beaches. Enjoy it! 

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<![CDATA[Weekend Forecast Becomes More Clear]]>420502403Wed, 26 Apr 2017 13:05:54 -0400https://media.nbcconnecticut.com/images/160*120/gfs_t2maf_slp_ma_13.png

Warmer temperatures and some sunshine by Friday and Saturday - I can't wait! The forecast is becoming more clear as we get a nice consensus on our computer models.

There is one interesting piece of the forecast Saturday afternoon and evening showing up on some of our computer models. Both the GFS and NAM show a surge in instability late in the day Saturday which would introduce a risk for thunderstorms - and maybe even a severe thunderstorm. One thing we look at is mid level lapse rates - basically how quickly temperatures decrease with height about 15,000 feet up. The faster temperatures drop the more unstable the atmosphere is. These steep lapse rates are a hallmark of many of our high end severe weather events.

That said, there are lots of questions here including how much moisture we'll have in the low levels of the atmosphere and whether we'll have enough forcing to generate storms in the first place. These are open questions but given the instability surge modeled on some of our models this is worth watching.

As for temperatures - upper 70s and low 80s seem to be a good bet Friday and Saturday. The Short Range Ensemble Forecast (SREF) above shows good agreement for both days with a gradual warming trend. There still some uncertainty, however, as to what will happen on Sunday. Winds will become onshore which should result in a drop in temperatures. How cool and how much cloud cover we see is still a bit up in the air - stay tuned.

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<![CDATA[Rain Continues This Evening]]>420421263Tue, 25 Apr 2017 20:24:41 -0400https://media.nbcconnecticut.com/images/160*120/CODNEXLAB-2km-VA_WV-ir-ani24-201704252307-100-100-raw.gif

A sprawling cut-off low off the Carolinas is drifting north and will produce locally heavy rain in Connecticut later tonight. These cut-off lows can produce all sorts of problems (like the flash flooding in North and South Carolina over the past few days) but this one is weakening rapidly. 

If nothing else tonight's rain will be a welcome drought-denter. We're not talking about enough rain to cause flooding (a big puddle under a railroad bridge doesn't count) but we are talking about enough to fill up streams, rivers, and even reservoirs some. Another drop in a bucket that needed a whole lot of filling after 2 years of below normal rain. 

So far rainfall amounts have been below 1/2 inch but there are some signals that things will pick up. For one, colder cloud tops (indicative of higher clouds and even some thunderstorms) are developing off the coast of Delaware and streaming north. 

Our computer models show a surge in instability (CAPE) tonight which is a good sign for heavy rain. Convective Available Potential Energy is an acronym you'll hear a lot in the warm season and it tells us how unstable the atmosphere is. Our models show modest instability developing across southern New England after 10 p.m. this evening which should favor some more vigorous updrats leading to some thunderstorms and downpours. 

Where thunderstorms develop (especially if they linger over the same towns) we have the potential to see 1"-2" of rain in a relatively short period of time tonight. Right around midnight some towns will see one heck of a downpour. I don't think an additional 1.5" or 2.0" will be widespread but some areas will get a very good drink of water tonight. The NAM model shows localized pockets of 2" of rain which is reasonable tonight in a few towns given the large amount of moisture and the instability that develops. 

Beyond tonight things gradually improve over the next 36 hours. By Friday temperatures near 80 degrees will be common inland!

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<![CDATA[From Rain to Warmth]]>420258363Mon, 24 Apr 2017 13:11:55 -0400https://media.nbcconnecticut.com/images/160*120/gfs_tprecip_ma_11.png

Another drought-denting rain is on the way Tuesday and Wednesday. Another inch of rain will put another small dent in the drought that was about 2 years in the making. 

Rain will begin Tuesday morning and continue off and on through Wednesday. The setup is fairly common this kind of year with a big cut-off low off the southeastern U.S. drifting up the coast. This is the kind of setup that can deliver flooding rains to Connecticut in April BUT this system is weakening dramatically. Still, a period of locally heavy rain is a possibility in some towns later Tuesday and Tuesday night.

Even though the low weakens as it moves up the coast there's quite a bit of moisture that will move in. The graphic above is what's called "precipitable water" (PWAT) and it's a good way of looking at how much moisture exists throughout the atmosphere. What we've done here is compare the PWAT values for Tuesday night to what's typical for late April - values are ~200% of normal so that indicates there's a lot more moisture in the air than there typically is this time of year. This shouldn't come as much surprise, though, when you see where the air is coming from. A long fetch of southerly winds is transporting moisture from the Caribbean and southern Atlantic Ocean right into New England. 

It appears as though the peak of the rain will be Tuesday night. The low level jet stream (about 5,000 feet above our heads) will peak Tuesday evening and night and that is when there's a maximum in low level convergence and moisture transport. That's when we'll get the wettest.

How much rain are we looking at? Most of our computer models have between 0.5" and 1.5" across that state and that looks reasonable. This will not be enough for flooding. With a low that's weakening (and, as a result, modest amounts of lift in the atmophere) it will be tough to see truly excessive precipitation even with an unusually high amount of moisture. I should note, however, that some of our short range ensemble members (see graph above) do show over 2" of rain. While unlikely, this would be a possibility especially if thunderstorms develop.

We're still on track for an extended period of warm weather later this week through early next week. At least one or two days near 80F seems likely. 

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<![CDATA[A Warm Start to Summer?]]>419978453Thu, 20 Apr 2017 12:42:07 -0400https://media.nbcconnecticut.com/images/215*120/off01_temp042017.gif

Today the National Weather Service released their 3-month forecast for May, June, and July. It's a scorcher for the east coast. The June-July-August forecast is just as warm for New England.

The NWS is predicting a better than 50% chance of warmer than normal conditions for all of New England south through Florida. Most of the United States with the exception of the northern Rockies and northern Plains is also expected to experience a hot summer. 

Here in Connecticut a greater than 50% chance of a hot summer means there's less than a 50% chance of either "normal" or "below normal temperatures this summer. "Warmer than normal" is defined as the 10 warmest in the last 30 years while "colder than normal" would be 10 coldest in the last 30 years, etc.  

This forecast isn't a huge surprise given how warm our recent summers have been and continued warming due to climate change. 

Of course things can change. While these kinds of outlooks show skill (compared to say rolling a die or shaking a magic 8 ball) they're not always correct. Even saying there's <50% chance of a normal or below normal summer doesn't preclude that from happening. We shall see! 

<![CDATA[Subtropical Depression 1]]>419903723Wed, 19 Apr 2017 19:43:47 -0400https://media.nbcconnecticut.com/images/180*120/avn_lalo-animated041917.gif

Unless you're a weather geek you probably haven't heard about the subtropical depression that formed in the Atlantic Ocean today. It didn't make it in any of my weather segments today as it sure didn't pass the, "who the heck cares" test. 

A subtropical depression is like a hybrid tropical-non tropical storm. Our nor'easters in the winter are non-tropical low pressures. Hurricanes like Gloria, Carol, 1938, and Bob are tropical lows. But like so much in meteorology it's really not cut and dry and there's a continuum or spectrum of lows - fully tropical, fully non-tropical, and somewhere inbetween. This is a somewhere inbetween storm. The biggest difference between tropical and non-tropical storms is where they derive their energy with the former gaining energy from warm ocean waters and the latter from processes including fronts, jet stream disturbances, and other such things.

Here's an official definitition of a subtropical system from the National Hurricane Center:

Subtropical Cyclone:

A non-frontal low-pressure system that has characteristics of both tropical and extratropical cyclones. Like tropical cyclones, they are non-frontal, synoptic-scale cyclones that originate over tropical or subtropical waters, and have a closed surface wind circulation about a well-defined center. In addition, they have organized moderate to deep convection, but lack a central dense overcast. Unlike tropical cyclones, subtropical cyclones derive a significant proportion of their energy from baroclinic sources, and are generally cold-core in the upper troposphere, often being associated with an upper-level low or trough. In comparison to tropical cyclones, these systems generally have a radius of maximum winds occurring relatively far from the center (usually greater than 60 n mi), and generally have a less symmetric wind field and distribution of convection.

If Subtropical Depression #1 manages to strengthen a bit more it will even get a name - Arlene! It's a nice looking swirl 830 miles west of the Azores that's no threat to land and expected to dissipate shortly. Besides the fish this thing is impacting no one. 

As usual, there was a bit of complaining this morning on weather twitter about whether this system should have been declared, whether it would have been declared one in the past, and whether this whole thing is a waste of time. I fall on the side of sure - let's call it what it is a "subtropical depression" and even name it if it strengthens. But that doesn't mean it's worth spending time talking about - it's nothing more than a swirl of clouds in the middle of nowhere that manages to get a fancy web page and graphics built for it because the National Hurricane Center called it something. 

So now you know what a subtropical depression is whether you've been curious or not. 

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<![CDATA[Turning Cooler]]>419734563Tue, 18 Apr 2017 13:01:48 -0400https://media.nbcconnecticut.com/images/160*120/ireland12456.jpg

After an amazing week vacationing in Ireland where it was between 50 and 60 dregees I sort of chuckled when the pilot informed the cabin it was 81F at JFK on Sunday. Bradley Airport managed a wild 88 degree temperature on Easter Sunday! But for those who like the warmth we've got a change on the way for the next week or so.

The weather pattern has changed. A big ridge of high pressure that pumped warmth up from the south and kept a westerly wind in New England is being replaced by a somewhat persistent  trough and periods of onshore wind. This time of year wind direction is critical for our temperatures with exceptionally cold water in the Atlantic Ocean. 

There are signs, however, that by the end of April a return to unseasonable warmth may occur. For example, both the Euro and GFS models rebuild a southeast ridge of high pressure and move a milder airmass in here in the Day 11-Day 15 time frame. 

While we'll have to deal with a few cloudy, showery, and cool periods over the next week or so if you like warmth there are some positive signs ahead.

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<![CDATA[A High Risk for Forest Fires]]>419194134Tue, 11 Apr 2017 17:45:35 -0400https://media.nbcconnecticut.com/images/213*120/Fire+Danger3.png

Meteorologist Josh Cingranelli here. I'm guest writing 'On Ryan's Radar' while he's taking some much deserved R&R in Ireland. 

Abnormally high temperatures coupled with gusty winds are leading to an increased risk of brush and forest fires.

Conditions are dry with relative humidity values between 20 to 30 percent. 

One of the reasons conditions become so dry this time of year is because of the lack of leaves on the trees. 

The leaves help to provide moisture into the atmosphere in a process called transpiration. 

The dry conditions have caused a high fire danger level.

When the fire danger is high, very high, or extreme open burn permits become invalid. Click here to check out the latest fire danger level.

The dry conditions will continue through the end of the week. Relative humidity values will range from 20 to 30 percent with breezy conditions. 

Fire officials across the state urge everyone to be vigilant when discarding any ashes. 

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<![CDATA[Heavy Rain, Flooding, and Storms]]>418502933Thu, 06 Apr 2017 20:59:34 -0400https://media.nbcconnecticut.com/images/213*120/CODNEXLAB-GOES16-Infrared-14-42Z-20170406_871-877-10-10011.gif

9:00 P.M. Update: As we expected strong thunderstorms rolled through between 4 p.m. and 7 p.m. While there was a report of nickel size hail in Higganum the storms mainly behaved otherwise with occasional pea size hail, lightning and heavy rain.

There were several reports of wind damage in Smithtown, Long Island and also a 58 mph wind gust at Mount Sinai Harbor to our south. Minor flooding is still expected on some rivers in the state as today's rain runs off. 

Rainfall totals in many areas did underperform as the storms were exceptionally fast moving (90 mph!) and there was a fairly large dry slot over Connecticut during the afternoon.

11:00 A.M. Update:  Rain has tapered off for the time being but heavier rain will move back in this afternoon through early evening. Thunderstorms across the Mid Atlantic - from Washington, D.C. to North Carolina will approach later today.

9:00 A.M. Update: The rain has arrived and there is the potential for some flooding this afternoon and early evening. There are a few things to note about today's flooding potential:

  • Flooding should be isolated and relatively minor. Rainfall amounts will likely fall short of what's needed for more widespread or significant issues.
  • Rainfall amounts of 1"-2" likely across the state - most areas will be closer to the 1" amounts, however.
  • Small rivers and streams may approach bankful and some urban areas may see poor drainage flooding.
  • Larger rivers (Farmington, Yantic, Quinnipiac, etc) should remain in their banks - flooding is not expected on these rivers.
  • The Connecticut and Housatonic Rivers should experience minor (typical in spring) flooding Friday and Saturday as swollen tributaries feed the two biggest rivers in the state.

One thing we will be monitoring closely this afternoon is the potential for strong thunderstorms between 4 p.m. and 7 p.m. While severe weather is not likely - I can't rule out a stronger storm. We have a very stable layer of air near the surface but there will be a significantly unstable layer just off the ground - we call this elevated instability. 

With this in mind I expect we'll see some elevated thunderstorms that could result in small hail, very heavy rain, and lightning. While unlikely, occasionally these thunderstorm can produce strong winds at the surface. Winds only 2,000 feet above the ground are near hurricane force so if those storms can punch through the stable layer near the ground we could see strong winds. Again this is unlikely but something we'll be watching closely. 

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<![CDATA[Thursday Soaker]]>418452293Wed, 05 Apr 2017 22:30:37 -0400https://media.nbcconnecticut.com/images/213*120/Model+NAM+Accum+Precip+CT2+%281%29.png

Another round of rain on top of saturated ground could result in minor flooding in parts of Connecticut Thursday. Our computer models show somewhere between 1.00" and 2.00" of rain across the state with the potential for locally higher amounts in a few towns. 

Even with this additional heavy rain most of the rivers in Connecticut can handle it. The Farmington River (hydrograph pictured below) is expected to remain below flood stage as is the Yantic River and Quinnipiac River. Smaller rivers and streams, however, may see quick rises tomorrow afternoon as the rain runs off quickly. Urban areas with poor drainage may also be succeptible to flooding. Don't be the person we get video of with a stalled out car under a Metro North underpass! 

One other item of interest tomorrow afternoon is the potential for a strong thunderstorm in southeastern Connecticut. Some of our computer models develop quite a bit of elevated instability (nearly 1,000 j/kg of CAPE) just above the ground. Additionally, very strong wind fields will be present with winds near hurricane force about 2,000 feet above our heads. While there is a very strong stable layer forecast to be present near the ground thunderstorms can do funny things and occasionally mix down stronger winds from aloft even in the presence of steep inversions/stable layers. At the very least, lightning, thunder, downpours and small hail are possible.

Most of the rain will taper off after 6 or 7 p.m. as dry air moves in from the south. 

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<![CDATA[Big Warmth Expected Next Week]]>418225693Tue, 04 Apr 2017 11:21:40 -0400https://media.nbcconnecticut.com/images/160*120/gfs_t2max_boston_32.png

Signals are growing for an impressive surge of warmth next week. It won't be record breaking but it certainly will be a welcome change after an unusually cold March across Connecticut.

The key this time of year is the wind direction. A wind out of the south, east, north - or any combination of the 3 isn't going to get warmth into southern New England. Water temperatures in the 40s off of Cape Cod and Long Island make it almost impossible to warm when the air is blowing off the Atlantic. The key is to get a westerly wind off the land and that is what we're expecting early next week.

Right now, we have 70F forecast for Tuesday but that number may need to be increased. In fact some of the raw model numbers we're looking at have temperatures approaching 80 degrees by Tuesday! 

Looking back a bit, this morning's rain was pretty impressive as we expected. Most areas picked up about an inch of rain in a short period of time while some spots in southwestern Connecticut managed over 2" of rain resulting in some minor flooding. 

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<![CDATA[A Wet Week of Weather]]>418027213Mon, 03 Apr 2017 22:29:46 -0400https://media.nbcconnecticut.com/images/213*120/C8h4mmQW0AA5ICY.jpg

Two storms each dropping 1"-2" of rain - finally! Combined with snow melt to our north this rain may even be enough to result in minor flooding on some of the larger rivers in the state. 

The heaviest rain tomorrow will fall during the morning commute with occasional rain during the midday and afternoon hours. A few thunderstorms are possible tomorrow along with any heavier downpours that develop.

One of the things we'll have to watch tomorrow is a localized are of heavy rain in southern Connecticut with strong onshore flow. Some of the NCAR ensemble members show a localized band of 3" of rain near the Merritt Parkway. This is a phenomenon that has been documented before (Colle and Yuter, 2007) as southerly flow over the ocean is slowed by friction over Long Island and Connecticut resulting in convergence - in addition to increase lift forced as air is forced up and over the small hills on Long Island and Connecticut. A local minima in precipitation is observed over Long Island Sound.

Another storm approaches on Thursday and that may result in even more rain. The GFS model shows very good odds of over 2" of rain in Hartford by the time the Thursday storm is over (each line represents a different computer model precipitation forecast) and other models have even more rain.

If the rain gets you down - don't worry. There is a strong signal for above normal temperatures next week as a southwesterly wind flow develops and warm air moves toward New England. 

Right now we're forecasting 70F on Tuesday. Who's excited?

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<![CDATA[What Drought?]]>417909073Sun, 02 Apr 2017 21:02:05 -0400https://media.nbcconnecticut.com/images/160*120/gfs_tprecip_neng_29.png

About 50 percent of the state is still under a "severe drought" but it sure seems like our fortunes are changing. Windsor Locks managed an "above normal" March with 3.93" of precipitation while I managed 4.95" in West Hartford! This week, like the last several, also looks awfully stormy.

The European model shows good odds (>50 percent) of more than 2" of rain for southern and western Connecticut over the next 7 days. With snow melt up north along with locally heavy rain we may see a period of minor flooding on the Connecticut River. You can see impressive rises possible based on rainfall and snow melt from the GFS ensembles.

While it will take time to completely eliminate the drought we're moving in the right direction. If we can string together 2 more months of above normal precipitation we may finally be able to put this drought in the rear view mirror. 

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<![CDATA[Icy and Rainy Night]]>417808783Fri, 31 Mar 2017 18:53:47 -0400https://media.nbcconnecticut.com/images/160*120/NAMNE_850_temp_018.png

Today's storm is beginning to pick up in intensity as colder air filters in from the north this evening. Already freezing rain has developed in many locations in Litchfield County and also the northeast hills as rain falls into subfreezing temperatures near the ground. The biggest concern for tonight is the potential for tree damage and power outages as freezing rain glazes up power lines and trees across the hill towns.

The NCAR ensemble from this morning is extremely bullish on the freezing rain potential with up to 1" of icing tonight! While the NCAR ensemble frequently overdoes freezing rain we need to monitor this closely.

You can see the issue on this sounding off the NAM which shows a warm layer that's sufficient to melt snowflakes. How warm that warm layer is will determine how much precipitation falls as freezing rain and how much as sleet. 

This is the area we're highlighting for freezing rain issues this evening - particularly above 600 or 700 feet. 

By morning there is the possibility of a flip back to snow or sleet along the I-84 corridor and possible as far south as Norwich and Middletown. Cold air will sink south as a band of heavy precipitation develops across Connecticut, Rhode Island, and Massachusetts. This is a tough, tough forecast. Don't be surprised to see a burst of mix developing around daybreak in many areas that just get rain tonight. 

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<![CDATA[Ice and Rain to End March]]>417685273Thu, 30 Mar 2017 15:20:11 -0400https://media.nbcconnecticut.com/images/213*120/Model+RPM4+Precip+Cloud+CT+Web.png

This is probably a fitting way to end March 2017. The month has been nearly 5 degrees below average compared to January 2017 which was 6.6 degrees above average! As I wrote about yesterday late March/early April is full of weird storms (2016 April freezing rain and 2014 morning commute surprise snow) that have given forecasters fits and ticked off the vast majority of Connecticut residents ready for spring. 

A storm is going to dive south of southern New England and produce a period of rain, sleet, freezing rain, and even a bit of snow. If you're excited for a big snowstorm - temper your enthusiasm immediately! This storm is looking more and more like a slushy/icy mix for areas north of I-84 and a mainly rain event south of there. Even in the Hartford area a lot of what will fall will likely be in the form of rain.

The "snow/sleet" forecast is actually fairly straightforward. Plenty of mid level warmth will limit the amount of snow we can get. In fact most areas see very little. The bigger question is what form the ice takes Friday evening and Friday night. Is it ice pellets or freezing rain. Ice pellets (or sleet) is the bouncy stuff that is a nightmare to shovel and not great to drive on but it sure beats freezing rain which clings to powerlines and trees and can result in all sorts of problems.

The key to figuring our what we'll see is how thick and how warm the warm layer is aloft AND how cold temperatures are right at ground level. First we'll start at the ground. This product from the NCAR ensemble shows the probability of temperatures below 32F at the surface at 8 p.m. Friday. There are good odds for <32F temperatures for the hilltowns later Friday. 

Upstairs the forecast is a bit more convoluted. I can look at the 850mb pressure level (about 5,000 feet up) and see what the temperatures are doing there and you can see a significant spread between the NAM and the GFS. The NAM is warmer with a low farther north and the GFS is colder thanks to a low farther south.

So which one's right? The truth likely lies in the middle and that's where the European model has been. The Euro shows a warm layer Friday night and Saturday morning which is enough to preclude snow and likely deliver a period of sleet and freezing rain in the hills north of I-84 and rain farther south.

Here's the bottom line on the Friday/Saturday storm...

  • Mainly light mix of snow, sleet, and rain on Friday with little if any road issues given strong March sun angle, temperatures generally above 32F, and light rates of precipitation. There is still a small chance for a bit of snow accumulation around daybreak if we get an unexpected heavier birst around the morning commute.
  • Heavier rain, sleet, freezing rain mixture Friday evening and Friday night.
  • 1"-2" of liquid precipitation expected with a few slushy inches of accumulation possible in the hills.
  • A prolonged period of icing (freezing rain) remains possible in the hills though I think prolonged sleet is more likely. If we get a lot of freezing rain it could lead to tree and power line issues. This would also result in minimal accumulation (i.e. the 2"-4" won't happen). In this event the valley locations around Hartford will just see rain as surface temperatures will be above freezing.
  • An icy mix lingers into Saturday morning and tapers off by mid morning. A flip back to snow from the wintry mix is possible even in the valley/Hartford area - this is one thing we'll watch closely.

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<![CDATA[Friday Mix]]>417526843Wed, 29 Mar 2017 20:58:51 -0400https://media.nbcconnecticut.com/images/213*120/C8HIHzCXUAAGfPw.jpg

Over the last couple years we've had a few unusual late season snow and ice events. Last April we managed an extremely rare springtime freezing rain event that produced 0.20" of ice accretion in New Haven during the day on the second coldest April day on record! 3 years ago I had a spectacular forecast bust with a burst of heavy snow that suddenly occured during the morning commute dropping 5" of snow in only about 2 hours on parts of the I-91 corridor on March 31, 2014.

With those two storms in mind - what kind of surprise does Friday's storm have in store for us? We know we're going to see a good burst of precipitation - particularly Friday evening and Friday night - with over 1" of liquid falling. Good for the drought! The temperature profile is what makes this storm so tricky. As I wrote about yesterday there's not a good cold high pressure anchored to the north so getting excessive snowfall is going to be tough. Take a look at this time-height cross section of temperature for Bradley Airport off the European model. You can see a pocket of warmer air a few thousand feet above the ground with colder air below it. This would favor sleet and freezing rain. 

The GFS model is colder than the Euro and a blend of the two would yield a period of snow, sleet, and even some freezing rain across areas north of I-84. We will have to monitor this closely as a degree in either direction would mean a drastic change in the forecast. Here's what I'm thinking right now:

  • Light mixture of snow, sleet, and rain during the day Friday. While a few slick spots are possible Friday morning if snow develops around daybreak most of the day should be problem-free on the roads. Light snow and sleet rates and the strong sun angle should do the job to keep roads wet.
  • Heavier precipitation will develop Friday evening and Friday night. 
  • Mainly rain is expected along the shoreline Friday evening/night with occasional sleet pellets.
  • Inland areas will see a mixture of sleet and rain along I-84 in the higher elevations and in the hills sleet and freezing rain may be the dominant precipitation type. Some snow is possible as well near the Massachusetts border with several inches of accumulation possible.
  • The storm will peak during the overnight hours with everyhing winding down shortly after daybreak Saturday.
  • While there is likely to be an icy mix and slushy accumulation north and west of I-84 (especially in the hills) there are two less likely things we'll have to watch foe. One is the potential for a colder solution which would mean more snow - including in the valley north of Hartford. The second thing to watch for is the potential for an extended period of freezing rain in the hill towns which would weigh on trees and powerlines.
Let's hope April winds up better than March. I'm ready for spring!

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<![CDATA[Wintry Mix for the End of March]]>417391443Tue, 28 Mar 2017 20:42:35 -0400https://media.nbcconnecticut.com/images/187*120/ne_f90.png

March is supposed to go out like a lamb - not like this! On the 20th anniversary of the epic April Fools storm of 1997 it appears that parts of southern New England may see another winter storm. 

Here in Connecticut the storm is going to be much too warm for all snow but a messy mix of snow, sleet, freezing rain and rain appears likely. The storm will be of a somewhat long duration with a period of some snow/mix as early as Friday morning with some mix continuing off and on through Friday night. 

At this point, I'm not expecting a major event here in Connecticut. This time of year getting a major winter storm is tough to do - and with no cold high pressure anchored to the north this becomes all the more challenging to accomplish. A cold and raw mixture of rain, sleet, and snow seems more likely than a more significant wintry event.

That said, both our GFS and European models show the potential for some mixed precipitation and problems. The GFS model sounding valid prior to daybreak Friday shows a column cold enough for snow even in the valley around Hartford. If this were to verify we'd have to worry about the potential for a bit of slick travel in the morning prior to a change to rain. 

Another way of showing the temperature profile for this storm is to look at this time-height cross section from the European model at Bradley Airport which shows a classic signature for ice or sleet with warm air located above colder air near the surface. You can see this on the right side of the image below where temperatures 6,000 feet up reach 2C or 3C while temperatures near the ground are just below freezing. 

At this point, I wouldn't expect a major winter event but some nuisance kinds of accumulation are possible - even in valley locations. Of course, it's possible this turns a bit colder and more wintry - especially in the hilltowns. One concern would be a stronger low pressure south of Connecticut Friday night with a period of heavier lift in the atmosphere in precipitation. This could promote a flip to heavy wet snow. Another possibility worth watching is an extended period of icing in the hills but given the time of year and lack of a good and cold high pressure to the north this seems unlikely to me right now. 

We'll be watching this closely over the coming days. 

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<![CDATA[Winter Strikes Back]]>416777133Tue, 21 Mar 2017 20:54:16 -0400https://media.nbcconnecticut.com/images/160*120/gefs_t850a_conus_5.png

After a gorgeous 2 days of weather we're going to see a dramatic change by tomorrow, Thursday and the weekend. The first item of interest in unseasonably cold weather for the next 48 hours. 

Temperatures will be nearly 20 degrees colder than average with a dramatic shot of Arctic air. 850mb temperatures (about 5,000 feet above our heads) will be between 15c and 20c colder than average! That's a big negative anomaly. While there is a surge of more typical March air on the way for Friday and Saturday the weekend forecast remains intriguing.

A storm to our west will send moisture streaming into New England Sunday and Monday. This is a classic "overrunning" setup with warm air advecting north into New England BUT near the ground it's a much different story. The big key to the forecast is a large high pressure over northern Quebec that will nose south into New England. This will lead to a wedge of low level cold air with warmer air aloft and as a result the possibility for ice.

Let's take a look at the ECMWF (euro) and GFS temperature forecast. The Euro forecast shows a layer of mild air about 7 or 8,000 feet above us with colder air below it. This is an inversion. Snow will melt into rain drops in the warm layer and then either refreeze into an ice pellet or reach the ground as freezing rain. The GFS temperature forecast (shown here as a SKEW-T) shows a similar setup for later Sunday with an area of above freezing air above a shallow but notable subfreezing layer of air close to the ground.

At this point it's unlikely we'll get a major winter storm (i.e. excessive amounts of ice) but this is looking like it could be a nasty and unpleasant mix with some icy travel and chilly temperatures - especially for the time of year. Obviously lots can change over the next few days but this is something we're going to be watching closely. 

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<![CDATA[Blizzard Delivers for Some and Falls Short for Others]]>416212873Wed, 15 Mar 2017 11:34:23 -0400https://media.nbcconnecticut.com/images/160*120/C65cHUVWsAA-v4v.jpg

Snowfall totals ranged from 1" to 24" across the state from yesterday's blizzard that peaked during a remarkably impressive 2-3 hour snow blitz around midday. I've heard a number of complaints and compliments from our viewers on the forecast. Along the shoreline there's no question the storm was a bust - across the interior there's not question the storm lived up to expectations.

The biggest reason the forecast missed along the shoreline was the fact the storm passed approximately 75 miles west of where I thought it would. This analysis from the Storm Prediction Center shows the low tracking inside or west of Block Island. This is a low pressure track that is sure to bring warm air into a large chunk of the state. 

In West Hartford I measured 12.9" of snow (it likely would have been a bit higher had a been able to measure more frequently and earlier) and it melted to 2.02" of liquid! That is an extremely dense snowfall with a snow:liquid ratio of 6.4:1 which is well short of a typical 10:1 ratio.

The snow flakes grew at temperatures that were between -5C and -10C while the favored region for snow flakes (-12c to -18c) was dealing with a dry slot. Basically, only small snow flakes were able to develop during the day. As warmer air moved in we saw sleet and in southern Connecticut some rain.

An old rule of thumb for figuring out who will get the heaviest snow is to look at the mid level low pressure (around 10,000 feet). Lows are tilted back to the west with height and this low is typically well west of the surface low. In yesterday's storm was over Philadelphia. We saw a band of intense lift out ahead of the low (see that purple over Connecticut) associated with something we call frontogenesis (basically forces a vertical circulation to form resulting in areas of rising and sinking air). But - the areas that really cashed in were located along and west of that low track. In fact some areas in the Catskills saw almost 40" of snow!

Some of our computer models had that low much farther west (over Connecticut or even just east of us) up to 24 hours prior to the storm. Had that tracked a bit farther east we would have seen huge totals - even down to the coast.  

So what did we learn? Our computer models struggled with the western trend right up until Tuesday morning. Credit where credit is due to the NAM and RGEM models for keying in on a warmer and western solution. This was on the far western solution of the European Ensembles (80 or 90% of them were east of where the storm tracked). Additionally, always respect the mid level dry punch. The drier air that moved in effectively shut off good snow growth and resulted in substantially lower snowfall rates than one would typically expect. That said, our forecast for almost the entire I-84 corridor worked out great with a record March snowstorm at Bradley Airport - 15.8".

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<![CDATA[On Ryan's Radar: March Blizzard Moves Closer]]>416013793Mon, 13 Mar 2017 12:07:05 -0400https://media.nbcconnecticut.com/images/160*120/nam_total_precip_neng_16.png

There has been a jump to the west with the forecast track of tomorrow's blizzard. This introduces a few issues including a mix with rain and sleet south and east of Hartford and may push the heaviest snow band a bit farther to the north and west. 

This morning I updated the snow forecast to illustrate where we expect the heaviest snow bands to set up. I wouldn't be surprised if these bands moved 20 to 30 miles either west or east by tonight. 

The numbers that our models are showing are eyepopping. A band of tremendous lift will move through tomorrow morning and midday with a ferocious period of snow. I expect the heaviest snow to fall between 10 a.m. and 5 p.m.

At the peak of the storm a surge of warmer air will move in to the shoreline east of New Haven and a period of rain and sleet now appears likely. 8"-12" of snow is expect in parts of southeastern Connecticut with heavier totals farther north and west where it stays all snow.

There are a few things to keep in mind. This map of the European model shows possible location of low pressure tomorrow afternoon. If one of the western-most solutions verifies (over Rhode Island) we will deal with mixing all the way back to I-91 and a dry slot that would shut the snow and mix off early. If it's a bit farther east (say east of Nantucket) the heaviest snow band of 18"+ has the potential to wind up over Hartford and New Haven.

Still, the most likely scenario is a foot of snow for Hartford and New Haven and over 18" of snow in the Litchfield Hills. This is also the area that's being highlighted by the European model with the highest probability of over 18" of snow.

Additionally, at the peak of the storm we are expecting winds to gust between 40 and 60 mph. Sporadic tree and powerline issues may develop especially where the snow is of a wetter consistency. 

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<![CDATA[On Ryan's Radar: March Blizzard On The Way]]>415980793Sun, 12 Mar 2017 17:30:53 -0400https://media.nbcconnecticut.com/images/213*120/C6vP2tbWoAAvDTc.jpg

This has all the makings of a classic. A powerful nor'easter will move up the coast producing a heavy burst of snow throughout southern New England. Of course - there are still some questions that I'll dive into in just a bit. First, what we know.

  • Over 6" of snow is extremely likely with over 12" of snow now a good bet.
  • Current forecast is 12"-18" of snow statewide with locally higher amounts to 24" - especially in the hills. 
  • Snow begins around daybreak with the heaviest snow between 10 a.m. and 8 p.m. This time table may change a couple hours in either direction.
  • Wind gusts over 40 mph at the shoreline may result in blizzard conditions. 
Now, what we don't know.
  • Where exactly does the storm track - too far east and it's more of a glancing blow (still 6-12" of snow) or too far west and we introduce some mixing issues at the coast and dry slot issues everywhere (still 6-12" of snow). Something in between (which is what we're expecting) and we get more than a foot. 
  • If the storm takes the "perfect track" and winds up near Cape Cod we will get crushed. Where the heaviest snow band sets up (we're talking 18"-24" totals here) is unknown... is it eastern Connecticut or the Northwest Hills. We won't even begin to have an idea until tomorrow morning.
  • How strong will the winds be on the coast - this will be determined based on the strength and exact track of the storm. 50 or 60 mph winds are possible with a stronger storm tracking near the Cape.

We pretty much have two camps of models - some east (GFS) and some west (Euro, NAM, UKMet, etc). The model differences are due to how the computer models interact two pieces of energy in the jet stream. There's one disturbance over the Great Lakes that is effectively capture a juicy, moisture-laden disturbance swinging northeast from the Gulf of Mexico. 

The GFS suite (including the ensembles) take the system a bit more seaward - with a late capture. Basically the system isn't absorbed quickly and we wind up with a slightly weaker and a slightly farther east solution. Incidentally, the GFS ensemble members that are stronger are much farther west. Still, even with the eastward jog there's a sizable signal for excessive snow. 0.7" to 1.0" of liquid on average would be a 6"-12" snowstorm across the state. Big but not epic.

A track farther west like most of our models have would mean a beast of a storm. The question will then become how far west and whether or not any dry slot issues develop. Generally you want to be undernearth or just northwest of the mid level low pressure about 10,000 feet up - where this tracks is critical to figuring out where the heaviest snow band will be. For example the NAM, pictured above, keeps the 700mb low to our west and then sort of develops it overhead Tuesday afternoon. This would favor heaviest snow totals in the Northwest Hills and Berkshires, effectively shut off the heavy snow quickly after 3 p.m. as dry air races in aloft, and introduce mixing/precipitation type issues in southeastern Connecticut. 

The midday European model, however, has a classic mid level low track which would ensure epic snow totals over 20" in many areas. Additionally, powerful winds would develop Tuesday afternoon as the low strengthens extremely rapidly just southeast of us. At this point, based on the pattern and a lot of the guidance, we're leaning toward the Euro with some consideration for the lesser models. 

I'm very confident we're going to have a big storm - the question right now is how big. Are 10"-14" common or are we closer to the upper bounds? This has the potential to be extremely impressive so stay tuned!

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<![CDATA[Major Winter Storm Likely Tuesday]]>415947253Sat, 11 Mar 2017 12:03:20 -0400https://media.nbcconnecticut.com/images/160*120/gfs_pr6_slp_t850_neng_15.png

It's about as strong of a signal I've seen for a major winter storm 4 days ahead of time. A powerful nor'easter will develop after emerging from the Gulf of Mexico on Monday. At this point it's fair to say a significant storm is likely and I would be surprised if at least a portion of Connecticut didn't get a foot of snow.

The storm has all the makings of a blockbuster.

  • A deep and cold antecedent airmass with a sprawling large high pressure to the north. 
  • A bit of downstream blocking of the jet stream near Greenland.
  • A potent and moisture laden disturbance exiting the Gulf of Mexico with a second disturbance diving south from the Great Lakes. How these interact will be the key to where the storm tracks.

Let's look at our overnight computer guidance for example. The European Ensembles (the European model run 51 different times at slightly lower resolution with a few tweaks) shows a 50-70 percet probability of more than a foot of snow across Connecticut. The odds of 18" of snow are between 5% and 20%. For a 96 hour forecast these are huge probabilities!

Of course things can change a bit. The key is going to be the storm's strength at our latitude and how close to the coast does it track. Is the storm near Block Island or near Nantucket? If the storm tracks too far west we would introduce sleet and rain issues - if it's too far east the heaviest snow would miss us to the east (i.e. Boston and Cape Cod get clobbered while we get a lesser storm). This map shows all the different locations of the low from those 51 different European Ensemble members.

Here's what we can say right now:

  • A major coastal storm/nor'easter is likely on Tuesday and Tuesday night
  • The most likely start time is Tuesday morning with the peak of the storm Tuesday afternoon and evening. Let's say 3 p.m.-midnight as a first approximation.
  • 1 to 2 feet of snow is a good possibility just northwest of where this storm tracks. Whether that is in eastern New York, eastern Massachusetts, or Connecticut it's too soon to say. 
  • A jog to the west of the storm that introduces precipitation type issues (sleet and rain) is still a possibility.
  • Blizzard conditions and strong or even damaging winds are possible with this storm.
  • By later tonight and tomorrow we can start throwing out some preliminary numbers. I have a feeling they'll be big. 

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<![CDATA[Friday Snow and a Bigger Tuesday Threat]]>415819743Wed, 15 Nov 2017 11:45:27 -0400https://media.nbcconnecticut.com/images/213*120/C6gjAEVWYAA_mXE.jpg

Editor's Note: This story is from March 2017.

Snow will be flying across most of Connecticut Friday morning. The morning commute looks sloppy. We're not talking about a major storm but I am expecting some issues.

The biggest question I have is how much dry air hanging out over western Massachusetts will sink south into far northern Connecticut? Will dry air eat up the snow in the lowest levels of the atmosphere in the Connecticut River Valley north of Hartford? This is definitely a possibility.

At this point a model blend/consensus indicates 2"-4" is a likely outcome in most locations with a bit more possible in a few spots near the shoreline and a bit less possible along the Massachusetts border. A few of our high resolution models have little, if any, accumulation near Windsor Locks and Enfield - this is a possibility if the dry air comes in a bit more impressive than currently modeled. 

What is looking more interesting is the potential for a major nor'easter on Tuesday. Many of our computer models now show a substantial snowstorm - capable of double digit snowfall totals. In fact, the European Ensemble has more than 60% probabilities of over 6" of snow on Tuesday across Connecticut - that's a really, really big probability for a storm 5 days out! This storm could be a big deal so stay tuned!

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<![CDATA[Winter's Back With 2 Snow Threats]]>415716103Thu, 09 Mar 2017 18:50:46 -0400https://media.nbcconnecticut.com/images/213*120/Launch+Custom+Map+4.png

A blast of Arctic cold bookended by two storm chances - winter is definitely back! The first threat for snow is Friday and at this point I'm becoming more bullish about the snow potential and I think my accumulation forecast from this evening needs to be increased.

This storm will feature a narrow band of heavy snow around daybreak Friday and the issue is going to be where exactly that narrow band sets up. There's a growing model consensus that a 20-30 mile wide band of up to 5" or 6" of snow is possible - but whether that's over Hartford or over New Jersey it is hard to say. The 18z GFS model has trended in a bullish direction with more than 0.5" of liquid (~5" of snow especially away from the coast where it is all snow) in the southern half of the state. 

While this GFS model is one possible - and snowy - solution other models such as the 18z NAM are much less impressive with less than 2" of snow across the state. So where do we go from here? The probabilities on our European Ensembles of more than 1" and 3" of snow seem reasonable - and they show the best probabilities (a 30% chance) of over 3" of snow right over the southern half of Connecticut. 

Putting this all together I think a solid argument can be made for statewide 2"-4" of snow with locally higher amounts. We'll wait for one more round of computer guidance before changing the numbers "officially". 

Snow may begin as a bit of right at the onset along the shoreline Thursday night and Friday morning before flipping over to snow. The snow should accumulate readily through daybreak and then gradually taper off. After mid-morning, even with flakes in the air, accumulation should be tough to accomplish on paved surfaces with warming temperatures and time to treat the roads. I do think that whoever gets under that heavy band could see an impressive 1-3 hour snowfall. This sounding off the NAM in Hartford reveals a classic signature for efficient snowflake growth with lift maximized at a temperature of -15C. Big, fluffy snowflakes. 

After temperatures in the 20s Saturday and Sunday - extremely cold for the time of year- storm 2 approaches on Tuesday. The pattern appears favorable for a nor'easter and the midday European ensembles show a 40% of >3" of snow on Tuesday which is a very high probability at 6 days out! 

A busy stretch of weather after a few weeks of early spring!

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<![CDATA[Cold Arrives But What About Snow?]]>415621533Tue, 07 Mar 2017 19:59:13 -0400https://media.nbcconnecticut.com/images/160*120/gfs_t850a_conus_17.png

An exceptionally impressive blast of cold air will settle over southern New England for a second weekend in a row. Temperatures at 850mb (about 5,000 feet above the ground) are expected to drop below -20C which is near record levels for March. The record based on weather balloon launches at Chatham, MA dating back to 1948 is -23C!

So yeah, it's going to be cold! The question is what about our snow threats. At this point it appears there are two distinct chances for snow - one on Friday and another on Tuesday. The earlier threat on Sunday appears to have disappeared with the storm track being shunted well south by this big blast of cold air. 

It's worthless to try and pin down details or go through every individual model run because as one would expect there's a lot of spread and uncertainty in the suite of models at this time range. The best way to assess the likeliehood of snow is not by freaking out over each model run 4 times a day but rather use "ensemble forecasting" which ideally represents a spread of likely solutions for any given storm.

Take the European ensembles for example. The Euro Ensembles are basically the European computer model run at a somewhat degraded resolution with 51 small tweaks 51 different times. For the Friday storm about 4 out of 10 European ensemble members have over 1" of snow here in Connecticut. 

This has been a relatively consisent signature over the last couple days. While a shift to the south could occur at this point I think at least some accumulation is a reasonable bet in a portion of the state. 

The more impressive storm potential is Tuesday of next week. At this point nearly 1 in 4 European ensemble members show more than a half foot of snow. This is a really strong signal for 7 days out and an indication that we'll need to watch this closely. 

Where we go beyond Tuesday is anyone's guess. Will the cold pattern relax and our early spring resume? We'll see. At this point we're forecasting a return to near normal temperatures by St. Patrick's Day. 

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<![CDATA[Weather Pattern Turns Stormy]]>415490353Mon, 06 Mar 2017 17:54:53 -0400https://media.nbcconnecticut.com/images/160*120/gefs_t850a_conus_21.png

It seemed too good to be true for winter haters. Our remarkable stretch of 60s and 70s in the end of February has come to an end and now we may see on heck of a flip not just to a colder pattern but also to a snowier pattern.

One thing that has been missing all winter has been the infamous "Greenland block" or a "-NAO". The negative North Atlantic Oscillation features anomalous warmth and high pressure over Greenland and forces a storm track south of New England and frequently is a precursor to east coast snowstorms. All of our computer models show this feature developing by the weekend and early next week.

The first system we're watching is a weak clipper system on Friday which is by no means a certain snow-maker. The 51-member European Ensemble suite of computer models has a 30 to 40 percent chance of seeing more than an inch of snow Friday. One note of caution is that light snow in the afternoon during March can prevent snow from readily sticking to the pavement - that wouldn't be reflected in the 30 to 40 percent probability.

What appears to be a more significant storm approaches on Sunday. There's a large amount of model spread right now that includes a Connecticut snowstorm on some of the enesemble members to a glancing blow on the GFS computer model to a complete whiff on the Euro. At this point all three are possible. What's not likely is a storm that cuts to the west and brings warm air in as the -NAO block should do its job and keep the storm south of us with the cold locked in as well.


Whether or not any of these snow threats (including a third threat around Tuesday of next week) comes to fruition what does seem likely is another shot of very cold air over the weekend. Right now we're forecasting highs in the 20s for both Saturday and Sunday at Bradley Airport.

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<![CDATA[Weekend Cold]]>415121903Wed, 01 Mar 2017 20:25:13 -0400https://media.nbcconnecticut.com/images/160*120/gefs_t850a_5d_conus_231.png

The last couple weeks of spring couldn't last forever. An impressive blast of cold will move in for the weekend with temperatures struggling out of the 20s in most towns on Saturday. With some wind and after our recent stretch of warmth it's going to be a rude awakening!

A big dip in the jet stream will allow the cold to sink south. You can see a sharp and somewhat impressive trough of low pressure over the northeastern U.S. 

The real chill moves in Friday night as temperatures drop into the teens with strong winds. 

While this surge of chill will seem impressive it's not going to last too long. A surge of milder than normal air lurks to the southwest of southern New England for Tuesday and Wednesday. 

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<![CDATA[Convoluted Severe Weather Threat Wednesday]]>415041093Tue, 28 Feb 2017 22:06:46 -0400https://media.nbcconnecticut.com/images/160*120/mgWeb_WRF_20170228-210000_ANE_ECONUS_F00243000_PwinterThickness_R4km.png

Right off the bat it seems important to say that the fact we're even discussing severe weather on February 28th is pretty wild. The setup is very very complex and very convoluted - this is a tough forecast!

There's no question that there is an elevated severe weather threat tomorrow. We have a very unusual (for the time of year) combination of shear and instability. These are the two pieces that are necessary for severe thunderstorms to develop. These graphs off the short range ensembles (SREF) show very impressive shear and enough instability for some really intriguing storms - including supercells!

But there are some big cavaets here. For one, it's unclear how the severe storms over the midwest and Great Lakes will evolve tonight. Secondly, there's not much of a trigger tomorrow afternoon and evening during the maximum shear/instability combo. What do I mean by that? The best forcing (i.e. cold front) is displaced well to the west. Just becayse we have a combination of shear and instability large enough for severe storms it doesn't necessarily mean storms will form but rather indicates that if storms form they have the potential to become severe.

Our in-house WRF model - the RPM - has been all over the place with where and when thunderstorms will develop. Other high resolution models (including the 3, 4, and 12km NAM) have been equally jumpy with location and timing of storm development. This adds to the uncertainty. 

The bottom line is that there is most certainly a severe weather threat tomorrow - including damaging winds and tornadoes. That threat, however, is conditional on thunderstorms developing in the first place during the late afternoon and early evening. For now we'll leave the severe weather impact at low/medium. If it becomes clear storms will develop and be coincident with maximum instability and shear in the early evening then the numbers will need to be boosted. 

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<![CDATA[Winter Severe Thunderstorms]]>414884843Thu, 02 Nov 2017 22:37:41 -0400https://media.nbcconnecticut.com/images/160*123/COVER+PHOTO.jpg

Severe thunderstorms in the winter are rare in southern New England. Saturday night's EF-1 tornado in Goshen and Conway, MA ranks up there as one of the most unusual.  

The radar signature for the Goshen/Conway tornado was one of the more impressive signatures you'll see around here. The amount of rotation was well in excess of the typical thresholds we have for tornadic storms. Not surprisingly, the tornado was on the ground for 5 miles and peaked in strength in the town of Conway (one town north of where my mom grew up, incidentally) with winds of 110 mph. To see something like this in June would be impressive - to do it in February is unheard of. Or is it?

Looking back through the weather archives there are several storms that have produced exceptionally unusual weather in the cold season. The first one I stumbled across I thought was a mistake - an F2 tornado on Martha's Vineyard on December 18, 1951. I was sure it was an error in the database but it wasn't. The description in a 1951 climate report sure makes it sound like a tornado. 

On December 18, 1951 snow fell from Washington, D.C. north to New England. A warm front appeared to be draped along the coast and south of the warm front temperatures made it into the 50s (I see a high temperature of 52F at the Edgartown, MA coop station). Apparently this warm sector was unstable enough to produce a significant tornado. 

While the 1951 December tornado on the Vineyard may have been the oddest winter severe weather event there have been others in the cold season of note. The March 29, 1984 nor'easter produced heavy snow, violent winds, and coastal flooding. In Southborough, MA a strange "downburst", as it was described flattened several acres of trees.

While this may have been more related to a gravity wave allowing powerful wind just off the surface to mix down to the ground (Blue Hill Observatory had a 108 mph wind gust about 600 feet above sea level) there may have been some convective element to this as well. Bizarre.

The Thanksgiving 2005 tornadoes in Maine on the warm side of a warm front occurred while areas just inland were getting snow (including Portland). Several homes were swept off their foundations.

Of course there was also last February's widespread damaging wind event from powerful thunderstorms during the overnight hours. That produced winds in excess of 60 mph and knocked out power to tens of thousands across the state.

While severe weather in the winter is unusual it's not completely unprecedented. As our climate continues to warm, and more atypical weather patterns develop over the northeast, it wouldn't surprise me if our "severe weather" season becomes more year-round but history shows us even over the past several decades there are cases of severe storms in the cold months over New England. 

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<![CDATA[Rare Winter Tornado Rips Through Western Massachusetts]]>414814793Sun, 26 Feb 2017 19:32:36 -0400https://media.nbcconnecticut.com/images/160*160/annefarrell.PNG

A violent thunderstorm tore through western Massachusetts around 7 p.m. last night spawning a tornado in the towns or Conway and Goshen just to the west of Northampton and Deerfield.

The tornado has been given a rating of EF1 with winds up to 110 mph according to the National Weather Service.

The radar imagery was extremely impressive when the storm was over the Berkshire foothills. This radar grab from 7:10 p.m. shows very strong rotation about 4,500 feet above the ground - about 100 knots of gate-to-gate shear. This is well beyond typical thresholds for tornadoes in southern New England (the median value for New England tornadoes is closer to 50 knots). 

The environment in Massachusetts did not appear particularly favorable for severe weather. While there was very strong low level shear there was limited instability. In fact, nearby soundings off our high resolution computer models showed <100 j/kg of CAPE which is very meager. That said, it is possible the actual environment was more favorable than our computer models indicated. 

Farther west, in Pennsylvania where severe weather yesterday was more widespread, values of CAPE were between 500 j/kg and 1,000 j/kg. In fact, a tornado was confirmed in Luzerne County, Pennsylvania near Wilkes-Barre along with golf ball size hail. 

This is the first tornado ever recorded in February in Massachusetts. What is so bizarre is that this severe weather event occured exactly one year after the epic overnight severe weather event in February that was so incredibly unusual. Look out on February 25, 2018 - we have quite the unlucky streak going here.

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<![CDATA[Don't Get Used to the Record Warmth]]>414732103Fri, 24 Feb 2017 16:40:19 -0400https://media.nbcconnecticut.com/images/213*120/Custom+List+6+%282%291.png

Today was the second warmest February day on record for inland Connecticut. Absolutely remarkable warmth today! The question so many are asking is whether or not we're done with winter. 


Today's warmth is being driven by an unusually powerful "Bermuda High" type pattern - pumping unseasonable warmth to the north. Full sunshine managed allowed temperatures to soar across the state - and even the shoreline managed to see temperatures around or just over 60F. With an onshore wind and water temperatures in the 30s this is a real testament to how anomalous the airmass was.


But - don't be fooled. The calendar is still in February and the long range computer model projections do not look particularly warm beyond day 7. Is it possible we won't get another inch of snow? Sure, but I wouldn't count on it.


Both the GFS and European computer models show a virtual flip to the jet stream pattern over North America. The persistent trough over the western U.S. responsible for the record snow and rain in California will be replaced by a ridge of high pressure. That teleconnects to a trough over the eastern half of the U.S. which will allow some Canadian cold to move south into New England. While the pattern doesn't look particularly cold - even a seasonable pattern is cold enough to produce snow in early March. 


With cold air nearby and a relatively active storm track some of our computer models are starting to show a few snow threats starting Friday of next week and lasting through March 10 or so. While we can't lock any of these in just yet I wouldn't put the shovels away for good.

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<![CDATA[Warm for Some, Cool and Dreary for Others]]>414639593Thu, 23 Feb 2017 16:22:02 -0400https://media.nbcconnecticut.com/images/160*120/CODNEXLAB-1km-LongIsland-vis-ani24-201702231845-100-100-raw.gif

If you love warm weather, living along the shoreline can be frustrating in the end of winter and beginning of spring. The reason? Long Island Sound's cold water. 

Today the mercury climbed to 65F at Bradley Airport - just shy of the daily record of 68F set back in 1990. Along the shoreline temperatures were stuck in the 40s for the better part of the day with a southerly wind blowing right in off the Sound.

Cooler temperatures are fine when the sun is out but today was grey and foggy at the beaches. Warmer air blowing over the cold Long Island Sound and Atlantic Ocean resulted in a persistent but shallow layer of stratus clouds that got about as far north as Wallingford and Middletown.

This is known as "advection fog" and it isn't terribly unusual for coastal Connecticut. Several warm and sunny spring days are ruined every year around New Haven as this fog rolls in. Another way to look at this is through the atmospheric temperature profile. 

This sounding from New Haven at 8 a.m. this morning shows how temperatures change with height. About 1,500 feet above the ground temperatures were in the mid-50s while temperatures near the surface were in the mid-40s. This temperature inversion allows low clouds and moisture to be trapped and can result in clouds and thick fog like we had today. Across inland Connecticut the inversion was mixed out resulting in almost complete sunshine and warm temperatures.

Today's cooler temperature and fog along the Sound was actually well forecast. Our computer models have improved immensely over the years and generally do a good job sniffing out foggy days like this. If you're in New Haven or Branford or Old Saybrook and want some sunshine - drive north for about 15 miles and you'll have plenty of it.

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<![CDATA[Weather's Impact on Connecticut's Worst Air Disaster ]]>414510893Wed, 22 Feb 2017 16:53:07 -0400https://media.nbcconnecticut.com/images/190*120/hvn.jpg

Just short of runway two at Tweed-New Haven Airport, Connecticut's worst aviation disaster occurred on June 7, 1971. Allegheny Airlines Flight 485 crashed into a row of East Haven beach cottages on final approach to Tweed, killing 28 people in a horrifying fireball.

Wednesday morning's plane crash was only a few hundred feet north of where Allegheny Airlines Flight 485 crashed. However, this most recent crash was likely not related to weather.

Visibility at 10 a.m. today was more than 10 miles, wind was light out of the southwest and the ceiling, or cloud base, was 7,500 feet above the ground.

The Allegheny disaster in East Haven more than 40 years ago was blamed on pilot error but weather played a large role in the accident. Fog and very low cloud ceilings obstructed visibility across the Connecticut shoreline on the morning of June 7, 1971, according to the National Transportation Safety Board report.


The conversation recorded by a cockpit voice recorder between Captain David Eastridge and First Officer James Walker indicated the extremely limited visibility on final approach for the flight that had left Trumbull Airport in Groton on its way to Tweed-New Haven Airport, just before impact. 


Three people survived the crash, but 28 passengers and crew members died.

According to the NTSB report, the deaths were due to asphyixiation or burns after the initial impact. The report concluded the probable cause of the accident was, "the captain's intentional descent below the prescribed minimum descent under adverse weather conditions, without adequate forward visibility or the crew's sighting of the runway environment."

Photo Credit: New Haven Register
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<![CDATA[From Unusually Warm to Unusually Mild ]]>414422873Tue, 21 Feb 2017 20:16:39 -0400https://media.nbcconnecticut.com/images/160*120/gefs_t850a_5d_noram_611.png

If you love winter weather the next 10 days look pretty brutal. A very impressive surge of warmth over the next few days will result in temperatures in excess of the 60 degree mark across areas away from the water.

Going into next week we're going to see some changes but the end result isn't going to be particularly cold but the 60s will be gone. A large dip in the jet stream will result in a surge of cold weather across a good chunk of Canada and the central and western part of the U.S. 

What is important to note is that the primary storm track that sets up will be primarily to our west. While this doesn't preclude the threat of wintry weather (i.e. a well timed high pressure to the north could result in snow or ice with a secondary redevelopment south of us) it does introduce a rain/mild risk as we head into March. I don't think our snow chances are over yet but nothing is poiting toward a cold and snowy pattern. Mild with some chances for snow is a better way of putting it. 

Snow lovers - don't despair. The fat lady is warming but she's not singing just yet. 

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<![CDATA[Springfield 'Tornado Scar' 6 Years Later]]>414255903Mon, 20 Feb 2017 14:53:21 -0400https://media.nbcconnecticut.com/images/196*120/TornadoScar.PNG

6 years after the 2011 Springfield tornado tore through western Massachusetts dramatic new satellite imagery captures the damage path covered in fresh snow.

The deadly tornado occurred touched down on June 1, 2011 at 4:30 p.m. in Westfield, MA. The tornado was on the ground for 39 miles and lasted over an hour before finally lifting in Southbridge, MA.

This satellite image was taken on Thursday, February 17th following the two snow storms that moved through the region. The satellite is called MODIS (Moderate Resolution Imaging Spectroradiometer). It's a high resolution weather satellite that takes snapshots of earth every 1 to 2 days. 

The satellite has a resolution of 250 meters - which is small enough to capture something as small as a tornado track.  The satellite is the size of a small school bus and it orbits the earth 438 miles above our heads.

The weather satellite clearly depicts the scar that the tornado left just north of the Connecticut border. The 1/2 mile wide tornado tore apart forests and neighborhoods and today the damage to the trees throughout Hampden County is still visible even more than 400 miles above the earth's surface.

The destruction was widespread, hundred of homes and businesses were destroyed and three people were killed. 

These photos show what a home in Brimfield, MA looked like prior to the tornado and afterwards.



Photo Credit: NASA
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<![CDATA[Evening Snow and a Thaw]]>413900133Wed, 15 Feb 2017 21:49:09 -0400https://media.nbcconnecticut.com/images/160*213/image1aa57akena.JPG

A burst of snow and even some thunder and lightning put down two pockets of accumulation this evening. One, as expected, occured in the Litchfield Hills where a persistent snow squall dropped nearly an inch of snow in some towns (0.8" of snow reported in Warren).

A second squall produced an area of accumulating snow from Haddam south to Killingworth and Clinton - temperatures dropped enough to flip the rain to snow. Very impressive for the shoreline given how mild it was when the squall started!

As temperatures drop this evening watch out for some pockets of black ice.

Going forward, people who love winter are going to get a bit sad. No real change to the thinking from yesterday with a prolonged period of above normal temperatures moving in. The 6-10 day temperature anomaly about 5,000 feet above our heads again today shows huge positive temperature anomalies across the eastern half of North America.

I don't think winter is done. While it is looking warm over the next 10 days we've been able to sneak a number of snow events into a generally warm weather pattern so far this winter. We'll see how this unfolds going forward.

Photo Credit: Jonathan Ventres
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<![CDATA[From a Blizzard to a Thaw]]>413717413Tue, 14 Feb 2017 14:35:33 -0400https://media.nbcconnecticut.com/images/160*120/C4oB5_sXAAAOCJS.jpg

The jet stream pattern across North America is going to experience a fairly dramatic shift over the coming days and the impact will be a surge of milder than normal air across a large chunk of the country - including Connecticut. While the core of the warmth will be west of us I think we're looking at a prolonged stretch of at or above normal temperatures. 


This is really being driven by a number of factors. The tropospheric "polar vortex" is strong and showing no sign of slowing down. A strong polar vortex - over the North Pole - is effectively keeping cold air bottled up over the Arctic. We call this a +AO (positive Arctic Oscillation).  Additionally, a persistent trough over the western US is going to bring another round of storms to rain drenched California. This teleconnects to a strong ridge over the central and eastern half of the country - this is a -PNA (negative Pacific-North America oscillation). 

With this in mind we expect a growing trend of warmer than normal temperatures. While it's always possible to sneak in a winter storm - or even a day or two of below normal temperatures - this is a pretty powerful signature for warmth over a good chunk of the country. The warmth begins in earnest by Sunday with the European Ensembles showing a better than 50/50 shot of high temperatures over 50 degrees.

Skiers shouldn't despair, however. Conditions have been incredible of late and a few days of warmer than normal weather won't do anything other than soften up the snow. What can be disasterous for ski areas is a warm rain storm with temperatures in the 50s but we're not expecting anything close to that. A few days with highs in the 40s or even near 50 with sunshine and cool overnights will just give us a taste of beautiful spring conditions a month early. 

Here's a look at the current conditions at our mountains here in Connecticut. 

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<![CDATA[A Busy Weekend]]>413465823Fri, 10 Feb 2017 22:39:17 -0400https://media.nbcconnecticut.com/images/213*120/C4QQtCsWIAM-h9j.jpg

Two storms this weekend on the way- it was another busy day at work! Tonight's snow isn't really that big of a deal but we're going to see a bit of accumulation. 1"-3" of snow should do it across the state with a bit of moisture and plenty of cold air around. 

One thing that's notable about the snow this evening is that it should be quite fluffy. This sounding shows a really, really deep layer of temperatures around -15C which should assure big and fluffy snowflakes. These flakes tend to pile up readily. 

Any snow tonight will wind down pretty quickly around daybreak tomorrow morning. Most of Saturday looks great! Sunday's storm looks a whole lot more impressive but man it's a tough one to figure out. An area of low pressure to our west is going to redevelop just south of us and turn into a pretty powerful storm east of Cape Cod.

The question is how warm will temperatures get before that storm redevelopment occurs. Can we lock in some cold? We're right on the line between heavy snow and heavy rain (with a bit of sleet mixed in too). The GFS shows this well with the 0 degree isotherm at 850mb (around 5,000 feet up) bisects the state. 

A subtle shift in storm track and/or subtle shift in temperature will make a huge difference here. Our forecast is basically a blend of the GFS and Euro right now (the latter being the snowiest and the former being the warmest/rainiest) but there's plenty of bust potential on either side here. I don't feel particularly confident in this one. Let's see what our overnight computer models show and we'll talk again about it in the morning :)

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<![CDATA[Major Snowstorm Begins]]>413263193Thu, 09 Feb 2017 13:50:11 -0400https://media.nbcconnecticut.com/images/213*120/C4ONaPyXUAAg9x-.jpg

Midday Update: The heaviest snow is beginning to taper off from west to east across the state. Already 12"-16" have been reported in some areas and along the I-91 corridor we will see accumulating snow (though not as heavy) through 4 p.m. or so. Drier air will filter in from the northwest later today and get rid of the snow once and for all.

One thing that's worth mentioning again is just how exceptional the thunder and lightning has been with this storm. This has been one of the most prolific lightning producers I've ever seen. Remarkable.

Previous discussion below: 

Nothing has really changed since my post last night. A super impressive quick hitting storm is going to result in exceptionally heavy snowfall rates over the next few hours. Lots of lightning and thunder will occur to - this storm is going to be exceptional.  I'm using a lot of adjectives and superlatives for this storm because it deserves them. 

Most of our computer models have at least 1.0" of liquid across the state and I do think there will be a narrow band of incredible snowfall rates later this morning. Here's the reason why.

An area of low pressure is going to close off at about 10,000 feet above our heads and that is a hallmark of all of our big snowstorms in New England. Being under or just to the northwest of this feature is critical in getting into the best banding. 

One feature that's also been consistent in our computer modeling is the fact we're looking at violent upward motion where the temperature is close to -15C. This is the temperature at which snowflakes form most efficiently AND the favored type of snow crystal is a dendrite. Dendrites tend to pile up and accumulate quickly as the branches of the snowflakes get intertwined with one another. You can pull off crazy snow:liquid ratios when this signature develops - sometimes on the order of 20:1. 

Here's the bottom line...

  • 10"-18" statewide - if the banding really goes to town and becomes persistent we could see even higher totals in a localized area.
  • Extremely heavy snowfall rates 7 a.m. to 2 p.m. shutting off from west to east.
  • Snow winds down between 2 p.m. and 6 p.m.
  • Snow will be of a  heavy consistency first and then become a bit fluffier as the storm goes on.
  • Wind gusts up to 40 mph are possible on the coast especially

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<![CDATA[Snowstorm Turning Into a Beast]]>413225603Thu, 09 Feb 2017 11:34:14 -0400https://media.nbcconnecticut.com/images/160*120/hiresp_tprecip_neng_32.png

I've got to say - I'm really, really, really impressed with how this storm is shaping up. It's looking more and more likely that we're going to see a band of epic snow rates for a period tomorrow morning and midday. I eschew weather hyperbole but this one looks like the real deal.

This storm will be a bit different than many of our "big ones" due to its speed. We're only looking at a 4-6 hour window of really heavy snow. If this storm was moving anyslower we'd be talking about over 2 feet of snow - but it's trucking pretty fast to the east. With that in mind there will be some limit as to just how much snow we can get. The storms speed - and intensity - introduces another problem into the equation and that's the fact we're going to see exceptional snowfall rates at the storm's peak - possibly up to 4" per hour. That is enough to basically immobilize the state for a period of time. This storm will be very bad at its peak.

The biggest reason we're expecting these heavy snowfall rates is a band of very strong convergence will set up about 10,000 feet up. This a classic signature for heavy snow with powerful winds slowing to a crawl overhead - essentially forcing air parcels to pile up and rise. The acceleration of air in an upward direction is how we get clouds and precipitation - and in this case snow. 

As I mentioned yesterday one of the things we're watching closely is the fact this strong "lift" or vertical motion is occuring where the temperature is around -15C up way above our heads in the clouds. That is the temperature at which snow flake growth is the most efficient AND the favored crystal type is a dendrite which allows snow to become fluffy and pile up quickly. A 15:1 ratio of snow to liquid is possible where this lift is maximized near -15C in the atmosphere.

I'm pretty confident there's going to be an area that gets more than 14" - maybe as much as 18". Again, the upward bound here is somewhat limited in that we're only going to have a short window of exceptionally heavy snow - it's a quick mover! Could there be more? Sure but let's not get too carried away just yet and also remember this heavy band will be very narrow geographically.

Where this heavy band sets us things are going to rip but it's important to note when these bands develop there tends to be bands of downward/sinking motion on either side of them. While some people get crushed other areas can miss out a bit. The haves and the have nots in a snowstorm (if my neighborhood is in a "have not" band I'll be livid and a supremely unpleasant person to be around tomorrow afternoon). Still, I think even with these "sucker holes" 8 inches of snow is a reasonable lower bound for most locations.

Here's the bottom line:


  • Snow develops across the state 5 a.m. to 8 a.m.
  • Heaviest snow between 8 a.m. and 2 p.m.
  • Snow gradually winds down 2 p.m. to 6 p.m.
  • 8"-14" will cover it in most areas - but a narrow band of higher snowfall totals is very possible. It's also conceivable that this heavy band sets up right along the I-84 corridor. 
  • Snowfall rates of 1"-4" per hour in some spots will make driving exceptionally difficult. This will be an extremely high impact storm given how quickly the snow will fall. 
  • Thundersnow is likely at the storm's peak.
  • Winds could gust to 40 m.p.h. in southeastern Connecticut but we are not expecting widespread wind issues or any coastal flooding.
What could go wrong:
  • The truly heavy snow with winds up setting up in one corner of Connecticut (say northwest or southeast) leaving the large population centers in one of those subsidence zones. A possibility - but not likely.
  • Storm trends weaker and the forcing doesn't verify as currently modeled. We'd still get the low end of amounts but the really exceptional snow rates never materialize and some of my adjectives wind up overdone.
  • Best lift winds up above or below the -15C level and snow ratios are much closer to 10:1 than 12:1 or 15:1 as we're currently thinking.
Hopefully you can stay home from work tomorrow and enjoy the storm. We'll have you covered all day on NBC Connecticut. 

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<![CDATA[Thursday Snowstorm]]>413101843Tue, 07 Feb 2017 21:46:01 -0400https://media.nbcconnecticut.com/images/160*120/gfs_6hr_precip_boston_9.png

It's been an unusually warm winter but most people don't realize we've had almost average snowfall across the state. Not surprisingly the next 48 hours will follow that trend with near record warmth Wednesday and a snowstorm on Thursday. 

Our current thinking is that we'll have a sizable snowstorm Thursday across all of southern New England. The worst of the weather will be between 7 a.m. and 2 p.m. Thursday with a pretty impressive blitz of snow - possibly on the order of 1"-2" per hour.

Right now we've kept the range fairly large as we'd like a few more computer model runs to get a handle on a more stable solution. Also, it's not clear which part of Connecticut is most likely to see banding of heavy snow develop - is it along the shoreline or farther north? Right now we don't know. What we do know is that the odds of a significant snowstorm have increased quite a bit today. The 21 member GFS ensemble shows all members producing over 3" of snow with most over 6" in Hartford. These are also calculated using a 10:1 snow:liquid ratio which is likely to be a bit on the low side with 12:1 or 14:1 more common.

One thing we're looking at is a band of very heavy snow Thursday morning. This is a time-height cross section of the NAM model which shows an area of very strong lift at temperature of -15C way above our heads in the clouds. This is critical as this is the temperature at which snowflakes grow the most efficiently AND the favored type of crystal is a dendrite which tends to pile up rapidly. This can increase the snow:liquid ratio. Where this overlap between lift and the -15C temperature level occurs very heavy snow is likely.

While we can't rule out more than a foot of snow in some spots I think our upper bound of 12" works for now (I know other outlets are talking about 18" of snow). Here's why...


  • Storm is a quick mover - heavy snow will only last 4-6 hours across most of the state.
  • The storm's track is still awfully far south of New England - most of our computer models have it passing underneath the 40N/70W "benchmark".
  • A subtle shift to the south could reduce totals overall - this is a possibility.
  • There's no closed 700mb or mid level low which tends to be a feature in almost all classic New England snowstorm - this storm has a broad area of strong convergence and frontogensis at 700mb but no rapidly closing or closed low. 
  • The 51 member European Ensemble has 0 members that produce over a foot of snow in Connecticut.
The bottom line is that this storm continues to look significant. There is still a chance a small shift in the storm south could result in less snow but at this point we feel pretty confident in the 6"-12" forecast. All of this winds down by Thursday afternoon. Happy shoveling!

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<![CDATA[Ice, Warmth, and Snow]]>412923813Mon, 06 Feb 2017 16:11:26 -0400https://media.nbcconnecticut.com/images/213*120/Model+RPM4+Precip+Cloud+Temp+CT+%282%29.png

There's going to be a lot going on over the next 3 days. Tomorrow's weather concern is ice, Wednesday's excitement is warmth, and Thursday's trouble is snow. Let's take it one day at a time.

The storm that is moving in tomorrow is only a shell of its former self. Sort of. Last week our computer models showed a powerful storm tracking near Toronto with all sorts of heavy precipitation moving into New England. That's no longer going to happen. Lighter amounts of rain will move in Tuesday morning but the problem remains that temperatures will be near 32 degrees as the rain begins. 

Temperatures above our heads will be well above freezing tomorrow - but at the ground a stale layer of cold air will be tenacious. There's a lot of inertia when it comes to dislodging cold and tomorrow won't be any different. As rain falls temperatures near the ground will be at or just below 32 degrees. For many areas just away from the Sound this could be an issue around daybreak with a few light showers. All it takes is a tiny bit of precipitation to ice up untreated surfaces!

While temperatures in the valley locations will warm above 32 degrees by midday the temperatures in the hills will not. In fact, it looks like a prolonged period of icing will occur in the Northwest and Northeast Hills where 0.1 to 0.25" of ice accretion is possible. Even by 7 p.m. tomorrow the NCAR ensemble model shows a >50% chance of temperatures below freezing for many places over 500 feet of elevation.

This is not enough ice to cause power outages but is enough to make any untreated walkway or driveway really slick. 

  • Brief period of icing possible in many areas around the morning commute. Treated roads will generally be OK but any untreated areas will be slippery.
  • By mid-late morning most valley and shoreline locations will be above freezing.
  • Prolonged freezing rain is expected in the hills tomorrow - and temperatures in some areas may never climb above 32 degrees. Thankfully ice accretion amounts should not be enough to cause tree or power line issues.

As for Wednesday - the cold at the surface will mix out allowing temperatures to spike. 60 degrees is not out of the question in some areas but right now we're predicting highs in the 50s.

I mentioned above that Tuesday's storm has become much less impressive over the last several days. One consequence of that is that a second piece of energy is able to swing far enough north to clip us with snow. Had the Tuesday storm been stronger the storm track would have been hundreds of miles farther south. 

Unfortunately, there's not much we can say about the Thursday storm other than accumulating snow is a possibility AND the storm as a reasonable shot of being decent (i.e. more than 4"). This storm is producing an unusually large spread of possible outcomes on our computer models. Take for instance the GFS ensembles (the GFS model run with slight tweaks 20 different times to show a range of possible solutions) which show a HUGE spread. Anywhere from 0" to 10" of snow for Hartford. 

That's about as detailed as we can get about this one - there's the potential for snow but I have no idea if it will be a big storm or we get brushed by with a few flurries or period of light snow. Small tweaks and changes in the jet stream pattern will mean a lot here. I get that a forecast of "we don't know yet" is annoying but as a scientist there's really not much more I can do at this point. This storm is showing a really unusual amount of spread in possible solutions.

As we like to say in TV... stay tuned!

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<![CDATA[Tuesday/Wednesday Storm Trends Warmer]]>412771413Sat, 04 Feb 2017 12:25:09 -0400https://media.nbcconnecticut.com/images/160*120/gfs_t2m_b_neng_19.png

Whether it's just noise at this early juncture or the beginning of a more substantial trend it's hard to say. There's been a notable jump to a warmer solution for the Tuesday and Wednesday storm which would mitigate the ice threat on the front end and allow temperatures to soar into the 50s on Wednesday.

At the onset, it still looks cold enough for some ice on Tuesday. You can see the light to moderate precipitation moving into southern New England with temperatures pretty close to freezing. This would ice some things up for the morning commute.

The biggest reason for the change is a change in the strength and location of a cold high pressure to the north of us. This high appears weaker over Quebec and is also getting dislodged and shunted east quickly. Without a strong high to our north feeding cold and dry air into New England we're not going to avoid a surge of very warm air coming in. 

At this point I'd still be on the lookout for wintry weather on Tuesday as this could easily change back to something a bit colder and more interesting. We'll see if the trend continues.

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<![CDATA[Quiet Weekend Followed by a Large Storm]]>412588043Thu, 02 Feb 2017 16:22:38 -0400https://media.nbcconnecticut.com/images/160*120/gfs_pr6_slp_t850_neng_25.png

For a couple days we've been watching a chance for a minor snow event on Sunday. This is becoming less and less impressive. A weak upper level disturbance will swing through and may be able to trigger a period of light snow on Sunday. At this point any accumulation is quite unlikely and I only have a 10% chance of measurable precipitation (0.01" of liquid or more) in the forecast.

The storm on Tuesday and Wednesday continues to look very impressive. Take today's European model valid Wednesday afternoon. It has a 971mb low (check out how far to the left that is on your home barometer) over southeast Canada. If this were to verify temperatures could approach the 60 degree mark along with periods of heavy rain and damaging winds. It would be quite a storm.

Even if the wet, windy, and stormy Wednesday happens exactly as the European model is depicting - the front end of the storm still looks snowy and icy. As the leading edge of the storm's moisture moves in a well positioned high pressure to the north will feed down a supply of cold and dry air. This argues for a period of snow followed by icing as warm and moist air rides up and over the cold air near the ground. 

All of our models show this potential on Tuesday - the Euro, the GFS, and many of their associated ensembles. Obviously at day 5 and day 6 the details will have to be worked out. Here are some of the questions we need to figure out the answers to.


  • How impressive does that high to the north get? Will it remain locked in and provide a more extensive period of ice and snow?
  • How quickly does the moisture move in - does this start Tuesday morning before dawn or hold off until later in the day?
  • How quickly does warm air flood in aloft... how much snow before the change to ice. 
  • How strong does the low to the west of us on Wednesday get? A strong low over Toronto like the Euro shows would assure a change to rain and strong winds here while a weaker and more strung out low would mitigate the wind threat and potentially lead to more prolonged icing.
Right now we can tell you that the most likely solution is a wintry mix on Tuesday and rain/wind/mild temperatures by Wednesday. When we get a bit closer we'll be able to get a bit more specific! 

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<![CDATA[Stormy Week Ahead]]>412452473Wed, 01 Feb 2017 15:57:18 -0400https://media.nbcconnecticut.com/images/160*123/ecmwf_apcp_f174_ne.png

The weather pattern over the next 7 days is anything but boring. A large storm to our west is going to bring in all sorts of issues Tuesday and Wednesday as it ejects out of the Rockies and heads toward the east coast.

In the winter we frequently look for a negative North Atlantic Oscillation / -NAO to force storms offshore and prevent them from cutting far to our west. In general, this kind of storm track can keep cold air locked in and prevent warmth from flooding north. Next week's storm won't have a -NAO to work with. Generally below normal heights over the North Atlantic and Greenland will help favor a track to our west - a warmer storm.

That said, there are still some interesting things to watch here. Both the GFS and Euro models bring a piece of this storm in on Tuesday. Enough lingering cold and a fairly well placed high pressure to the north of Quebec should provide enough cold air for a period of snow or mix. 

The main storm is still likely to cut to our west bringing in warmth on Wednesday with a period of rain. Temperatures in the 50s would be possible - especially away from the CT River Valley north of Hartford that tends to see cold air get trapped between the hills west and east.

If we're lucky we'll get a lot of rain out of this storm - we could use it. We'll have to watching the leading edge of whatever we get, however, as we could be dealing with a period of snow or ice. 

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<![CDATA[Snow Continues Through This Evening]]>412313833Tue, 31 Jan 2017 15:14:13 -0400https://media.nbcconnecticut.com/images/176*120/16473288_1440394399327519_2085433135843357189_n.jpg

Today's snow is behaving pretty much as expected. I did think the heavier snow this afternoon would be a bit more widespread but it has been relatively patchy. There have been occasionaly reports of heavy snow but the snow by and large has been of the light to moderate variety.

Not surprisingly, roads have been a mess with accidents all over the place. Cold pavement temperatures allow almost every flake to stick.

I do think the snow will have some staying power this evening. As the main batch of it moves through by 5 p.m. we will see an area of lift developing in the low levels of the atmosphere through Massachusetts and northern Connecticut. This should allow snow to continue at a light clip through later this evening and tonight. Some additional accumulation will be possible. By the time the storm winds down 1"-3" of snow should be the final range across the state. 

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<![CDATA[On Ryan's Radar: Burst of Snow Tuesday Afternoon]]>412217943Mon, 30 Jan 2017 20:57:15 -0400https://media.nbcconnecticut.com/images/213*120/C3babc0XUAIxk4D.jpg

It's not a lot of snow but the timing is unfortunate. A burst of snow is going to cause some issues for the evening commute Tuesday. It's a classic Alberta Clipper system diving out of Canada and heading toward New England. Anytime an upper level system dives underneath us this time of year it's worth watching.

One thing that I'm watching closely is a strong zone of lift in the lower parts of the atmosphere. A strong low level jet will lend itself to strong low level convergence and lift over Connecticut. It appears we're in the area where this low level forcing is maximized. This argues for a period of moderate to heavy snow across Connecticut right during the evening commute.

Right now I'm thinking 1"-3" of snow is likely across Connecticut. There is an opportunity for a bit more than 3" of snow - in the hills especially - if the snow is able to be "fluffy" in nature. At this point I don't see a huge signal for very light and fluffy snow (i.e. 15:1 or 20:1 snow to liquid ratios) but this will have to be watched. I do expect light snow to continue through most of the overnight across northern Connecticut and possibly through right around daybreak Wednesday.

Beyond tomorrow the weather pattern is looking active and more wintry. I expect several chances for snow or wintry mix through day 10. Stay tuned!

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