Is anyone else as excited as I am for some heavy rain!? This has all the makings of a soaker here in Connecticut. The GFS model (pictured above) is most impressive with over 4" of rain in spots! The European model (not shown) shows 1"-3" across the state - not quite as wet as the GFS but still quite a bit of water.
Two bursts of heavy rain - one tomorrow and another Wednesday afternoon and Wednesday night - will be very, very welcome across our dry state. So why are we looking at all this rain? We have two upper level disturbances that will swing through and each force a response with developing low pressure near southern New England.
One way to visualize this is to look at what we call the low level jet (LLJ) which is approximately 5,000 feet above our heads tomorrow. While the winds will be quite light here on earth just a few thousand feet up with wind will be whipping over hurricane force! The nose of that LLJ will tickle the coast of southern New England putting Connecticut in a favorable area for heavy rain. Think of it like this - strong winds blowing 60-80 mph are forced to rapidly decelerate over New England (to 30 or 40 mph). That forces air to converge and pile up forcing the air to rise. This convergent signature is a great signal for heavy rain.
So how much rain are we looking at? A fair forecast is 1"-3" of rain coming in two waves - one tomorrow and another later Wednesday. It's possible that some areas could receive 4" or 5" of rain where thunderstorms or banding develops. The 1"-3" range fits in well with the spread shown on the SREF models. This plume diagram shows the 21 members of the Short Range Ensembles for Hartford with most in that 1"-3" camp.
This is pretty much all good news with 1-hour flash flood guidance (how much rain needs to fall to produce flash flooding) values of around 2" across the state and 6-hour values between 2.5" and 3.0". We should generally be below these thresholds.
In case you're wondering how much rain we need to extricate ourselves from this drought? The National Weather Service estimates we'd be eliminated from any drought outlook if we picked up somewhere between 6" and 12" of rain. While we don't need it all at once we'll take what we can get!