Mesoscale Discussion 1350
   NWS Storm Prediction Center Norman OK
   0219 PM CDT Tue Jul 28 2020

   Areas affected...Chesapeake Bay region southwestward to northern
   North Carolina

   Concerning...Severe potential...Watch unlikely 

   Valid 281919Z - 282115Z

   Probability of Watch Issuance...20 percent

   SUMMARY...A gradual increase in convective coverage is expected over
   the next 1 to 2 hours, with stronger storms capable of producing
   strong/gusty winds.   Some tree damage may occur with a few of the
   more sustained updrafts.

   DISCUSSION...Latest surface analysis shows a weak/diffuse surface
   boundary crossing central Virginia at this time, with diurnal
   heating of the moist near-frontal boundary layer (around 70
   dewpoints) now pushing mixed-layer CAPE values into the 1500 J/kg
   (Chesapeake Bay area) to 2000 J/kg (north-central North
   Carolina/south-central Virginia) range.

   A gradual increase in convection is occurring across this area,
   particularly near the Danville Virginia/state border area -- as a
   weak/subtle vort max evident in WV imagery crosses the southwestern
   Virginia vicinity.  While flow aloft is rather weak across this
   region (west-northwesterly at 15 to 20 kt), upscale growth of the
   cluster into a more linear band could locally increase gusty wind
   potential.

   Farther north, slightly weaker instability and more isolated
   convective development is indicated.  However, with slightly faster
   flow aloft (20 to 30 kt westerlies per the morning IAD RAOB and the
   latest LWX WSR-88D VWP), locally strong wind gusts will become more
   likely over the next couple of hours as storms strengthen in
   conjunction with peak heating/destabilization.  

   At this time, WW issuance is not expected, due to marginal risk and
   isolated storm coverage.  However, any signs of potential for
   greater coverage of the more vigorous convection could warrant WW
   consideration.

   ..Goss/Bunting.. 07/28/2020

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

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

   LAT...LON   39417585 39007571 38177616 37297718 36257914 35938091
               36428119 36868013 37707968 38287895 38947814 39567653
               39417585