Mesoscale Discussion 1610
   NWS Storm Prediction Center Norman OK
   0120 PM CDT Thu Aug 26 2021

   Areas affected...Northwestern Maine

   Concerning...Severe potential...Watch unlikely 

   Valid 261820Z - 261945Z

   Probability of Watch Issuance...20 percent

   SUMMARY...Thunderstorms developing ahead of a cold front across
   eastern Quebec will move eastward with a risk for isolated damaging
   winds and hail this afternoon. Uncertainty on storm coverage remains
   considerable at this time. Convective trends will be monitored but a
   watch is unlikely.

   DISCUSSION...As of 18 UTC, regional surface observations and visible
   satellite data showed deepening cumulus along a fast moving cold
   front in the vicinity of Quebec City, QC. Downstream across portions
   of northern/western ME, daytime heating of a moist airmass with
   dewpoints near 70 f is supporting moderate destabilization. SPC
   mesoanalysis indicates 1500-2500 J/kg of MLCAPE has developed with
   additional destabilization likely in the coming hours. Increasing
   westerly flow aloft ahead of shortwave trough within interior Canada
   is forecast to overspread the unstable airmass through this evening
   with 35-45 kt of effective shear. 

   RAP forecast soundings show long but only weakly veering hodographs
   supportive of a mixed-mode of splitting supercells and line segments
   capable of damaging wind gusts and severe hail. Mesoscale trends and
   hi-res guidance suggest convective development along the front is
   likely over the next several hours though it is uncertain exactly
   how much storm coverage will develop. As storms track eastward
   across the international border additional development and some
   upscale growth into several clusters or line segments with a risk
   for damaging winds/hail appears possible but remains uncertain. The
   threat for isolated wind gusts and hail may extend eastward with
   time across much of central ME until storms begin to interact with a
   cooler and more stable maritime airmass near the Atlantic coast.

   ..Lyons/Dial.. 08/26/2021

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

   ATTN...WFO...CAR...GYX...

   LAT...LON   45197049 46287032 46946990 47496919 47436875 47306803
               46946772 46436784 45936820 45526858 45176902 45036930
               44786983 44807012 44977034 45197049