MESOSCALE DISCUSSION 1602
   NWS STORM PREDICTION CENTER NORMAN OK
   1243 PM CDT WED JUL 13 2011
   
   AREAS AFFECTED...PORTIONS OF VA/MD/NC
   
   CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 
   
   VALID 131743Z - 131915Z
   
   AT LEAST ISOLATED SEVERE TSTMS ARE LIKELY TO DEVELOP/INCREASE
   THROUGH MID AFTERNOON ACROSS PORTIONS OF MD AND MORE SO VA INTO NC.
   THE NEED FOR A WATCH IS SOMEWHAT UNCERTAIN...BUT SHORT-TERM
   DEVELOPMENTAL TRENDS WILL BE CLOSELY MONITORED.
   
   ALONG/SOUTHEAST OF A COLD FRONT...SATELLITE/RADAR TRENDS REFLECT A
   GRADUAL INCREASE IN TOWERING CU/INCIPIENT TSTMS ACROSS PORTIONS
   EASTERN WV/WESTERN MD IN VICINITY OF THE APPALACHIANS...WITH OTHER
   MORE RECENT CONVECTIVE DEVELOPMENT IN SOUTHWEST VA/NORTHERN NC AS OF
   1730Z. WHILE LARGE SCALE FORCING FOR ASCENT IS MODEST AND VERTICAL
   SHEAR DIMINISHES WITH SOUTHWARD EXTENT ACROSS VA INTO NC...THE
   GRAZING INFLUENCE OF INCREASINGLY CYCLONIC FLOW ALOFT VIA AN
   AMPLIFYING NORTHEAST STATES TROUGH...AND AN APPARENT WEAK MCV
   CURRENTLY OVER FAR EASTERN KY/FAR WESTERN VA...MAY BE FACTORS FOR
   THE SUSTENANCE OF ORGANIZED DEEP CONVECTION IN THE FORM OF
   MULTICELLS/SOME LINE SEGMENTS.
   
   CONSIDERABLE CLOUD COVER DOES EXIST...BUT AMPLE HEATING IS OCCURRING
   NONETHELESS WITHIN A RELATIVELY HIGH MOISTURE CONTENT AIRMASS WITH
   SURFACE DEWPOINTS GENERALLY IN THE LOWER 70S F. MORE CONTEMPORARY
   ADJUSTMENTS TO THE 12Z WASHINGTON-DULLES AND ROANOKE OBSERVED RAOBS
   REFLECT AS MUCH AS 2500-3500 J/KG OF SBCAPE. IN THE PRESENCE OF
   MODEST VERTICAL SHEAR/AMPLE INSTABILITY...IT DOES SEEM LIKELY THAT
   TSTMS WILL CONTINUE TO INCREASE IN COVERAGE/VIGOR AND SPREAD
   EAST-SOUTHEASTWARD ACROSS VA/NC...WITH THE STRONGEST STORMS CAPABLE
   OF MICROBURSTS/DAMAGING WINDS.
   
   ..GUYER.. 07/13/2011
   
   
   ATTN...WFO...AKQ...LWX...RAH...RNK...GSP...
   
   LAT...LON   35668175 36378133 37088017 39247836 39317760 37317681
               35407836 35668175