MESOSCALE DISCUSSION 0805
   NWS STORM PREDICTION CENTER NORMAN OK
   0501 PM CDT WED MAY 18 2011
   
   AREAS AFFECTED...SRN PA...NRN/ERN WV...NRN/ERN VA...MD...DE
   
   CONCERNING...SEVERE THUNDERSTORM WATCH 305...
   
   VALID 182201Z - 182330Z
   
   THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 305
   CONTINUES.
   
   WV IMAGERY AND RUC ANALYSIS FIELDS SHOW A VORT LOBE ROTATING NWD
   ACROSS THE MID ATLANTIC REGION LATE THIS AFTERNOON. BENEATH THIS
   FEATURE AT THE SURFACE...WEAK AREA OF LOW PRESSURE WAS POSITIONED
   OVER SERN VA AT 21Z. AXIS OF TEMPERATURES IN THE 70S EXTENDED NWD
   OVER ERN/NRN VA...WHILE TONGUE OF LOW TO MID 60S DEWPOINTS WAS
   PRESENT OVER THE DELMARVA AND ERN PA. AREA RESIDING BETWEEN THE
   SURFACE TEMPERATURE AND MOISTURE AXES /MAINLY ERN VA...DELMARVA
   REGION/ IS CHARACTERIZED BY MLCAPE VALUES AROUND 500 J/KG PER SFCOA
   GUIDANCE. IN ADDITION...30-40 KT MIDLEVEL JET IS AIDING IN EFFECTIVE
   BULK SHEAR VALUES NEAR 35 KT...FAVORABLE FOR ORGANIZED THUNDERSTORMS
   INCLUDING SPLITTING SUPERCELLS. GIVEN LACK OF ROBUST LOW-LEVEL
   VERTICAL WIND SHEAR PROFILES /0-3 KM SRH VALUES AOB 100 M2 S-2 BASED
   ON AREA VAD WIND PROFILERS/...PRIMARY SEVERE WEATHER THREAT WILL
   LIKELY BE LARGE HAIL AND DAMAGING WINDS DURING THE REMAINDER OF THE
   AFTERNOON/EARLY EVENING...PARTICULARLY WHERE INSTABILITY IS GREATEST
   /AS PREVIOUSLY NOTED/. AS BOUNDARY LAYER BEGINS TO COOL AND
   INSTABILITY DECREASES...SVR THREAT IS EXPECTED TO GRADUALLY
   SUBSIDE...WHICH MAY NEGATE THE NEED FOR ADDITIONAL WW/S.
   
   ..GARNER.. 05/18/2011
   
   
   ATTN...WFO...PHI...AKQ...CTP...LWX...PBZ...RLX...CLE...
   
   LAT...LON   41278073 39157539 36967540 39088074 41278073