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.