Strong To Severe Thunderstorms Are Still Expected This Afternoon & This Evening

A very active afternoon and evening is expected across Western and Central Mass with strong to severe thunderstorms likely. These thunderstorms are expected to bring with them flash flooding, wind gusts of 55-75 mph, quarter size hail, frequent lightning and a few tornadoes. Weather analysis as of just before midday reveals an area of low pressure is located near far northern New York State. A trough of low pressure extends southward into central and eastern New York State. This trough of low pressure is going to be the focus and the trigger to set off thunderstorms this afternoon and evening and quite a few of these thunderstorms will be on the strong to severe side. The atmosphere setup for these thunderstorms are going to include hot and very humid air producing a very unstable air mass. This will combine with a strong low-level wind shear that could lead to a thunderstorm environment that’s uncommon here in Western and Central Mass. Digging deeper into the data reveals that the winds in the lower part of the atmosphere are stronger than what they are in the mid and upper levels of the atmosphere. This is uncommon to see unless it’s during a tropical storm passage as usually we see stronger winds at the mid and upper levels than at the low levels of the atmosphere. Additionally, there is a fairly decent amount of turning of winds in the low-levels of the atmosphere at the time of this writing. All this means is that the wind profiles are supportive of sustaining severe thunderstorms that may try to rotate. There are a couple of factors that may dampen the severe weather threat (fail modes, so to speak). These include temperatures struggling to warm much more due to cloud cover leading to less instability than what is currently forecast. Also, it’s possible that a layer of warm and dry air could set up at about 20,000 feet above the ground. This could cap the atmosphere to some extent and lead to thunderstorms having a hard time really exploding up into the sky. This could limit the number of severe thunderstorms that actually occur during this afternoon and this evening. Here Are My Latest Thoughts On This Afternoon & Evening’s Weather: Thunderstorms are now beginning to develop over eastern New York State as of midday. I think that we’ll see these storms intensify with many of these storms becoming strong to severe over the next couple of hours. These strong to severe thunderstorms are expected to push into the area from the Berkshires to the northern Worcester Hills by about 1-3 pm or so this afternoon. These storms are expected to head in an east-southeasterly direction and reach areas from the lower Pioneer Valley of Western Mass through the western Worcester Hills to the I-190 corridor by about the 3-5 pm time frame. It’s currently anticipated that these strong to severe thunderstorms will make their way into the corridor that includes the Mass Pike, I-84, I-395 and Route 146 by about 4-6 pm. These storms are expected to continue into early this evening before pushing off to the southeast and ending by about 9-10 pm. Given the amount of wind shear, the degree of instability and the amount of forcing, we should see the potential for multiple individual supercell thunderstorms rather than a squall line. These severe thunderstorms will be capable of producing wind gusts of 55-75 mph, quarter size hail, frequent lightning, torrential downpours with a flash flood threat and a few tornadoes. I am watching this afternoon and evening’s severe weather threat extremely closely and will have many more updates as needed.