Mesoscale Discussion 1362
   NWS Storm Prediction Center Norman OK
   1204 PM CDT Fri Jul 31 2020

   Areas affected...Mid-Atlantic Region

   Concerning...Severe potential...Watch unlikely 

   Valid 311704Z - 311900Z

   Probability of Watch Issuance...20 percent

   SUMMARY...Isolated strong-to-severe wind gusts will be possible this
   afternoon with the strongest thunderstorms. Coverage of the
   thunderstorm threat should limit the need for a severe thunderstorm
   watch.

   DISCUSSION...A belt of modest mid-level flow exists atop a frontal
   boundary draped across portions of central Virginia. To the north of
   this boundary, a combination of northerly low-level flow, widespread
   cloud cover, and ongoing showers have kept surface temperatures in
   the 60s and 70sF. Along and south of the aforementioned boundary,
   surface southerly low-level flow and pockets of clearing skies o
   allowed surface temperatures to warm into the 80s to low 90sF. Given
   surface dewpoints across the region in the low-to-mid 70sF, a strong
   north-to-south gradient in CAPE exists, ranging from around 250 J/kg
   of most-unstable CAPE in the vicinity of Washington D.C. to around
   3000 J/kg of most-unstable CAPE across southern Virginia.

   Although forcing mechanisms for sustained, robust deep convection
   are nebulous, the combination of sufficient convergence along the
   aforementioned surface-boundary and weak large-scale ascent
   associated with small-scale perturbations within the modest
   mid-level flow will lend itself for isolated to scattered
   thunderstorm development this afternoon. The degree of instability
   and deep-layer shear on the order of 30 knots will be sufficient for
   clusters of multi-cell thunderstorms capable of producing isolated
   strong-to-severe wind gusts. Modest mid-level lapse rates (on the
   order of 6 C/km) should limit the overall hail potential.

   Given the expected isolated coverage of the convection, a severe
   thunderstorm watch is not currently anticipated this afternoon, but
   conditions will continue to be monitored.

   ..Marsh/Bunting.. 07/31/2020

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

   ATTN...WFO...PHI...AKQ...LWX...RAH...RNK...RLX...

   LAT...LON   38147998 38687802 38547559 37637516 36627633 35827987
               38147998