MESOSCALE DISCUSSION 0549
   NWS STORM PREDICTION CENTER NORMAN OK
   0112 PM CDT SUN APR 24 2011
   
   AREAS AFFECTED...SERN PA...NJ...DE...MD...NRN VA...WASHINGTON DC
   
   CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 
   
   VALID 241812Z - 241945Z
   
   PORTIONS OF SERN PA...NJ...DE...MD...NRN VA...AND WASHINGTON DC ARE
   BEING MONITORED FOR THUNDERSTORM INITIATION AND SUBSEQUENT INCREASE
   IN SVR WEATHER POTENTIAL/POSSIBLE WW ISSUANCE THIS AFTERNOON.
   
   MESOANALYSIS INDICATES A COLD FRONT WAS LOCATED FROM SERN NY WSW
   ACROSS CNTRL/SRN PA AND INTO THE OH VALLEY REGION AT 18Z.
   TEMPERATURES S OF THE FRONT ARE WARMING INTO THE 70S AND 80S...WHICH
   IS AIDING IN STEEPENING LOW-LEVEL LAPSE RATES AND BOUNDARY LAYER
   DESTABILIZATION. IN ADDITION...AXIS OF LOW 60S DEWPOINTS EXTENDS NWD
   INTO THE MID ATLANTIC REGION...WHICH IS AIDING IN WEAK TO MODERATE
   INSTABILITY...WITH MLCAPE VALUES EXPECTED TO PEAK AROUND 500-1500
   J/KG DURING THE AFTERNOON. THOUGH UPPER-LEVEL SUPPORT FOR ADDITIONAL
   AIRMASS DESTABILIZATION IS GENERALLY LACKING...COMBINATION OF
   CONTINUED SURFACE HEATING...CONVERGENCE/ASCENT ALONG THE COLD
   FRONT...AND VERTICAL MOTION FIELDS ASSOCIATED WITH APPROACHING MCV
   OVER SERN OH/NRN WV MAY AID IN THUNDERSTORM INITIATION DURING THE
   NEXT FEW HOURS. VWP WIND PROFILES AND RUC FORECAST SOUNDINGS
   INDICATE THAT VERTICAL WIND SHEAR IS FAVORABLE FOR BOTH SUPERCELLS
   AND FAST MOVING LINE SEGMENTS. THE PRIMARY THREAT ASSOCIATED WITH
   ANY SVR STORM ACTIVITY WILL LIKELY BE DAMAGING WINDS...THOUGH
   ISOLATED LARGE HAIL AND A TORNADO CANNOT BE RULED OUT.
   
   ..GARNER.. 04/24/2011
   
   
   ATTN...WFO...PHI...AKQ...CTP...LWX...
   
   LAT...LON   40827630 41067471 39877463 38607589 38207721 38227960
               39917811 40827630