Wednesday Severe Storms

We’re entering the peak of Connecticut severe weather season. Generally, Memorial Day through July 4th is the most active period around here for hail, strong winds, and tornadoes. Today may feature all 3 severe weather hazards in parts of New England and adjacent sections of New York.

As usual, the situation is a bit murky. Plenty of clouds this morning will be somewhat slow to break though there are signs of clearing skies upstream over portions of northern Pennsylvania and near Binghamton, New York. The sunshine will help destabilize the atmosphere.

The extent of that destabilization will determine how great the severe weather threat is. Our computer models show modest destabilization with MLCAPE between 1000 and 1500 j/kg in northwestern Connecticut, the Berkshires, and eastern New York. That’s sufficient – though not great (the Springfield tornado day had MLCAPE values >3500 j/kg). While some of the surface based CAPE values look surprisingly robust on the GFS the model is also spitting out some unrealistic surface dew points (i.e. 72F in Canaan at 5 p.m.) which is inflating the SBCAPE profile.

The trigger later today will be a shortwave that moves from upstate New York toward New England. The arrival of this points to a later show (storms will move in after 5?).

gfsNE_500_avort_018

 

If enough instability is realized the shear will be great enough for organized convection and possibly supercells. In fact, there is a noticeable veering wind profile with height by late afternoon which produces a clockwise curved (and somewhat long given the 850 mb flow >30 knots) hodograph.

The greatest threat for severe weather will be west of I-91 and along and north of I-84. The northwestern part of the state has the best chance at seeing severe weather. The threat will drop off quickly as you move east of 91 and south of 84.

bdl21hodo

 

All of this threat is conditional on the necessary instability developing. Needless to say there is a notable threat this afternoon so it bears watching. Follow @ryanhanrahan on Twitter for the live play-by-play this afternoon.

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