MESOSCALE DISCUSSION 0397
   NWS STORM PREDICTION CENTER NORMAN OK
   1254 PM CDT MON APR 20 2015

   AREAS AFFECTED...CNTRL AND NRN VA...NWRN NC...MD...SRN PA...SWRN NJ

   CONCERNING...SEVERE POTENTIAL...WATCH LIKELY 

   VALID 201754Z - 202030Z

   PROBABILITY OF WATCH ISSUANCE...80 PERCENT

   SUMMARY...SCATTERED SEVERE STORMS ARE LIKELY LATER THIS AFTERNOON
   WITH HAIL, DAMAGING WINDS AND PERHAPS AN ISOLATED TORNADO.

   DISCUSSION...VISIBLE IMAGERY SHOWS CU INCREASING ALONG THE LEE OF
   THE APPALACHIANS AS WELL AS INTO CENTRAL VA WHERE STRONG HEATING IS
   OCCURRING. DEEPER CU FIELDS ARE ALSO NOTED ALONG A STATIONARY
   BOUNDARY FROM SERN PA INTO SRN NJ. A N-S ORIENTED BAND OF CIRRUS IS
   ROUGHLY JUXTAPOSED WITH COOLING ALOFT...WITH DEEPER CU INTO THE WELL
   MIXED BUT DRIER AIR FROM WRN PA SWWD.

   OVER THE NEXT FEW HOURS...STORMS WILL FORM WITHIN THE BROAD LOW
   PRESSURE TROUGH...AND ALSO PERHAPS NEAR THE STATIONARY/WARM FRONT.
   STRENGTHENING WIND FIELDS WITH THE UPPER TROUGH WILL AID IN NWD
   TRANSPORT OF MOISTURE INTO AREAS THAT ARE CURRENTLY STABLE SUCH AS
   PA....LEADING TO STORM DEVELOPMENT.

   WHILE THE MAIN THREATS WILL BE HAIL AND WIND...LOW-LEVEL SHEAR
   AUGMENTATION ACROSS SERN PA...SRN NJ...DE...AND MD...AS WELL AS
   LOCALLY HIGHER DEWPOINTS INTO THE 60S F WILL OFFER A MORE FAVORABLE
   SETUP FOR AN ISOLATED TORNADO SHOULD CELLS MOVE INTO OR FORM IN THAT
   REGION.

   ..JEWELL/HART.. 04/20/2015


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

   LAT...LON   38397998 39147955 39557923 40327817 40397735 40297684
               40077600 39647596 38797649 38467679 37207824 36278007
               36218119 36538149 36998137 37418077 38397998