Mesoscale Discussion 0240
   NWS Storm Prediction Center Norman OK
   0844 AM CST Wed Mar 01 2017

   Areas affected...South-central PA...MD...DC...VA...and northwestern
   NC

   Concerning...Severe potential...Severe Thunderstorm Watch likely 

   Valid 011444Z - 011615Z

   Probability of Watch Issuance...95 percent

   SUMMARY...A widespread damaging wind threat will likely continue
   through the afternoon. Severe thunderstorm watch downstream of
   ongoing line of thunderstorms will very likely be issued by 1530Z.

   DISCUSSION...A line of strong to severe thunderstorms is advancing
   quickly eastward across the central Appalachians this morning.
   Damaging winds will remain the main threat with this convection
   given the linear mode and strong low-level winds noted on area radar
   velocity imagery. In addition, an isolated tornado may also be
   possible with embedded circulations within the line. The airmass
   downstream of the ongoing line is not overly unstable at the moment,
   with surface temperatures still generally in the 60s and dewpoints
   in the mid to upper 50s. However, some diurnal heating will likely
   occur as visible satellite imagery shows clearing along/east of the
   Appalachians, which should support sufficient instability to
   continue the damaging wind threat. Instability is more limited with
   northward extent into PA, and some uncertainty does exist concerning
   the potential for surface-based convection and the damaging wind
   threat there.

   ..Gleason/Hart.. 03/01/2017


   ATTN...WFO...PHI...AKQ...CTP...LWX...RAH...RNK...PBZ...RLX...
   MRX...

   LAT...LON   40337888 40317679 40007606 38027708 36287838 35977923
               36088048 36338174 40337888