More storms on Saturday? (6/23/12)

The forecast for widespread thunderstorms across the region on Friday worked out perfectly as several clusters/ of t'storms developed from ME all the way down through NJ.  There even turned out to be a little more in the way of severe weather than expected as there were numerous reports of damaging winds across the region, especially across western and northern CT including some reports of large hail!  While wind shear was not overly strong it was sufficient enough to help storm updrafts become organized and moderate instability gave the storms the fuel they needed to become strong and severe.  While the cold front which was responsible for providing the lift to spark today's thunderstorms will have moved off the coast by tomorrow morning the cooler/drier air is actually lagging a bit behind the front.  This cooler air will work into the region once a mid/upper level trough work through the region.  This will be occurring tomorrow, however, it will not be occurring quietly.

While temperatures tomorrow won't be nearly as warm today as the warmest of the low-level airmass will have worked off the coast with the front temperatures are still expected to be into the lower to perhaps mid 80's.  With still an abundance of low-level moisture around dewpoints will once again be into the mid 60's.  The combination of warm temperatures and high dewpoints will once again set the stage for moderate instability to develop across the region.  Some computer models are indicating as much as 1000-1500 J/KG of SBcape will develop tomorrow with the potential for as much as 2000 J/KG of SBcape along with LI values in the -3C to -5C range.  Unlike today, we will also be dealing with steeper mid-level lapse rates as mid-level cooling occurs with the approaching mid-level trough.  This will actually aid in some higher instability values tomorrow.

Not only will we be dealing with steeper mid-level lapse rates tomorrow but we will also be dealing with more in the way of wind shear as 0-6km shear values are expected to increase to the 35-45 knot range.  This will be more than sufficient to allow for storm organization and also lead to some mid-level storm rotation and some storms perhaps taking on supercell characteristics, especially if the stronger instability is realized.

All in all with the approaching mid/upper level trough and cold pool (500mb temps lowering to around -15C during the day) and potential for moderate instability along with adequate shear the potential once again will exist for the development of thunderstorms across the entire region.  While the entire region is under the threat the most numerous activity may occur across NH, southern ME, eastern MA and northern RI.  Any storms that develop tomorrow will have the potential to produce hail and gusty winds while the stronger/more severe storms will be capable of large hail and damaging winds.  All storms will produce torrential rainfall which could lead to pockets of flash flooding, especially for the areas which were hit hard by Friday's storms.

The timeframe for storms tomorrow should be anywhere from as early as 11 AM lasting to about 8 PM or so, however, far eastern sections of southern New England may see activity linger until 9-10 PM.  Once the trough passes through ,cooler and drier air will usher into the region and the threat for storms will be over...until Monday at least but we'll worry about this another day :)