Late Evening/Overnight T'storm Potential

Throughout the day today hi-resolution computer forecast models have been in rather strong agreement and have shown strong consistency for the potential for a line or multiple lines of thunderstorms to work through portions of New England during the late evening and overnight hours:

Typically (especially this time of year) we see the likelihood or potential for thunderstorms vastly decrease after sunset as the atmosphere typically begins to rapidly stabilize, however, there are several atmospheric ingredients in place which will allow for these thunderstorms to maintain and in fact, some of these ingredients will also allow for the possibility for a few of these thunderstorms to be on the strong to severe side and pose a threat for hail and strong wind gusts.  One of these key ingredients is the presence of rather steep 700mb-500mb lapse rates (strong change of temperature with height between about 10,000' and 18,000' off the ground).  SPC mesoanalysis shows 700mb-500mb lapse rates are between 6.5 C/KM to 7 C/KM.  These values which may actually steepen more towards 7 C/KM which will help keep the atmosphere rather unstable through the evening and into the overnight, even despite the loss of daytime heating:

With the presence of steep lapse rates, surface temperatures still predominately in the 70's, and surface dewpoints near 60F, this will yield most-unstable cape values as high as 1000-1500+ J/KG through the overnight hours and the RAP computer forecast model shows this.  This will provide the "fuel" to keep the storms going as they move in from NY:

The focus for a lifting/forcing mechanism is an approaching upper-level trough and associated shortwave energy and attendant cold front.  As this trough progresses east and the cold front moves closer, we will begin to see winds aloft strengthen which will provide adequate shear to help storm updrafts remain organized.  SPC mesoanalysis shows 30-40 knots of 0-6km shear across New England with 40-50 knots off to the west.  These values will push east into the region as the trough/cold front approach:

Several bufkit profile soundings across the region show a rather favorable environment tonight for not only thunderstorms but the possibility for a few strong to severe t'storms.  Looking at a bufkit sounding from the 18z NAM computer forecast model for Windsor Locks, CT we see pretty decent cape within the 0-6km layer (almost 500 J/KG!) and rather impressive hail cape (573 J/KG!!) along with very strong shear (39 m/s):

What this indicates is any thunderstorms will be accompanied by a great deal of lightning and would also have the potential to produce hail along with strong winds.  The greatest potential for thunderstorms appears to be across southern VT, southern NH, down through western/central MA and into norther-central CT.  Not everyone will see thunderstorms but for those that do they could pack a quick punch!