MESOSCALE DISCUSSION 1136
   NWS STORM PREDICTION CENTER NORMAN OK
   1245 PM CDT TUE JUN 23 2015

   AREAS AFFECTED...PORTIONS OF VA/MD AND DE/SOUTHERN NJ

   CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 

   VALID 231745Z - 232015Z

   PROBABILITY OF WATCH ISSUANCE...60 PERCENT

   SUMMARY...SEVERE THUNDERSTORMS MAINLY CAPABLE OF ISOLATED DAMAGING
   WINDS/SOME SEVERE HAIL ARE EXPECTED TO DEVELOP INTO THE REGION LATER
   THIS AFTERNOON. WHILE THERE IS SOME UNCERTAINTY REGARDING THE TIMING
   OF THE MAIN SEVERE THREAT...A WATCH ISSUANCE SEEMS INCREASINGLY
   LIKELY BY MID/LATE AFTERNOON.

   DISCUSSION...WELL AHEAD OF AN UPSTREAM COLD FRONT ACROSS THE
   MIDDLE/OH RIVER VALLEY...THE AIR MASS CONTINUES TO STEADILY
   HEAT/DESTABILIZE ACROSS THE REGION NEAR/EAST OF A SURFACE TROUGH IN
   THE LEE OF THE APPALACHIANS. TEMPERATURES HAVE GENERALLY EXCEEDED
   90F AS OF 17Z ACROSS MUCH OF VA/EASTERN MD AND DE/SOUTHERN NJ...WITH
   MLCAPE ALREADY ESTIMATED TO BE IN EXCESS OF 2500-3000 J/KG AS
   LOW-LEVEL LAPSE RATES CONTINUE TO STEEPEN. WHILE EARLIER
   AFTERNOON/LEE-SIDE ISOLATED DEVELOPMENT CANNOT BE RULED OUT...THE
   MOST PROBABLE SCENARIO IS EXPECTED TO BE THE EAST-SOUTHEASTWARD
   SPREAD OF UPSTREAM STORMS /INCREASING ACROSS PA AND NORTHERN WV
   EARLY THIS AFTERNOON/ INTO THE REGION LATER THIS AFTERNOON/EARLY
   EVENING. WITH THE REGION ON THE SOUTHERN PERIPHERY OF STRONGER
   WESTERLIES ALOFT...SUFFICIENT VERTICAL SHEAR/BACKGROUND FLOW WILL
   ALLOW FOR THE PERSISTENCE OF EAST-SOUTHEASTWARD-MOVING STRONG/SEVERE
   THUNDERSTORMS. DAMAGING WINDS/SOME SEVERE HAIL WILL BE A POSSIBILITY
   COINCIDENT WITH A HOT/UNSTABLE AIR MASS.

   ..GUYER/GOSS.. 06/23/2015


   ATTN...WFO...PHI...AKQ...LWX...RNK...

   LAT...LON   38197930 39467812 39747561 39217493 38097545 37067903
               38197930