Mesoscale Discussion 0381
   NWS Storm Prediction Center Norman OK
   0934 AM CDT Mon Apr 13 2020

   Areas affected...central and southeast PA...much of MD...northern VA

   Concerning...Severe potential...Tornado Watch likely 

   Valid 131434Z - 131600Z

   Probability of Watch Issuance...80 percent

   SUMMARY...The risk for damaging gusts and possibly a tornado or two
   will seemingly increase as storms develop through midday into the
   early afternoon.  A tornado watch is likely by 16z.

   DISCUSSION...Visible satellite imagery late this morning shows
   breaks in low-level cloud cover across western VA into the eastern
   WV Panhandle and into far south-central PA.  Water-vapor imagery
   indicates a compact mid-level shortwave trough over the upper OH
   Valley, and this feature is forecast to move into the central
   Appalachians by early afternoon.  

   Late morning observations over northern VA show temperatures warming
   into the mid 60s F with dewpoints in the lower 60s.  Forecast
   soundings and the gradually clearing of a high cloud shield from
   west to east, suggest additional heating will occur with
   temperatures reaching near 70 F by early afternoon over the northern
   VA/MD vicinity.   

   KLWX VAD data as of 1430z shows around 70kt flow at 2km AGL and
   100kt at 6km.  RAP model forecast soundings show a destabilizing
   airmass with MLCAPE ranging from 250 J/kg north to over 1000 J/kg
   MLCAPE over northern VA/MD/far southeast PA by early afternoon.  The
   intense wind profile and more than adequate instability will favor
   the development of strong to severe thunderstorms over the next
   couple of hours as storms develop/move east from eastern WV/VA into
   northern VA/MD/southeast PA.  Damaging gusts will probably accompany
   the stronger cores and a tornado risk may develop with any sustained
   supercell structure or mature bowing segment.

   ..Smith/Grams.. 04/13/2020

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

   ATTN...WFO...PHI...BGM...AKQ...CTP...LWX...

   LAT...LON   39047900 40927752 41097659 40707514 39967498 37407739
               38087879 39047900