Storm Prediction Center Mesoscale Discussion 1906

   Mesoscale Discussion 1906
   NWS Storm Prediction Center Norman OK
   1057 AM CDT Thu Aug 15 2024

   Areas affected...New Hampshire...Vermont...into
   Massachusetts...eastern New York State...Connecticut and Rhode
   island

   Concerning...Severe potential...Watch unlikely 

   Valid 151557Z - 151830Z

   Probability of Watch Issuance...5 percent

   SUMMARY...Increasing thunderstorm development appears probable
   through 3-5 PM EDT, with widely scattered stronger storms
   accompanied by a risk for localized, potentially damaging,
   downbursts and perhaps some small hail.

   DISCUSSION...Boundary-layer destabilization is underway across much
   of western New England into the Adirondacks and Catskills, with
   continuing insolation beneath the western flank of a modest
   mid-level cold pool associated with a slowly moving mid/upper trough
   near the Atlantic Seaboard.  Forcing for ascent, associated with one
   or two perturbations pivoting through this regime, has been
   supporting some thunderstorm activity spreading southward within
   generally light (10-20 kt) northerly deep-layer mean flow across
   western Maine, with consolidating surface outflow slowly beginning
   to spread southwestward into western New England.

   With further boundary-layer destabilization, which may include CAPE
   increasing up to 1500+ J/kg, and weakening of mid-level inhibition,
   model output suggests that the outflow boundary, and orographic
   forcing along the higher terrain to the west, will provide a focus
   for increasing thunderstorm development through 19-21Z.   Despite
   the weak nature of the wind fields and shear, modestly steep
   lower/mid-tropospheric lapse rates evident in forecast soundings may
   allow for sufficient negative buoyancy in downdrafts to support
   localized damaging surface gusts in stronger storms.  Some small to
   marginally severe hail might also not be out of the question.

   ..Kerr/Thompson.. 08/15/2024

   ...Please see www.spc.noaa.gov for graphic product...

   ATTN...WFO...GYX...BOX...BTV...ALY...

   LAT...LON   45807107 44967115 44277135 43307060 42117106 41917201
               42197395 43337459 44067379 44887299 45287238 45807107