MESOSCALE DISCUSSION 2219
   NWS STORM PREDICTION CENTER NORMAN OK
   1239 PM CDT FRI SEP 30 2011
   
   AREAS AFFECTED...PORTIONS CENTRAL-ERN NC...SERN VA.
   
   CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY 
   
   VALID 301739Z - 302015Z
   
   TSTMS FCST TO DEVELOP BEGINNING NEXT 1-2 HOURS AND INCREASE N
   COVERAGE THROUGH MID-LATE AFTERNOON OVER DISCUSSION AREA.  SVR GUST
   POTENTIAL MAY DEVELOP IN STEP WITH THAT INCREASE IN COVERAGE...AND
   ALSO...STRENGTHENING DEEP-LAYER SPEED SHEAR RELATED TO APCH OF
   MID-UPPER TROUGH.
   
   VIS IMAGERY SHOWS BANDS OF DEEP CU AND TCU DEVELOPING OVER COASTAL
   PLAIN.  IN THAT CORRIDOR...BOUNDARY LAYER IS RELATIVELY DEEP AND
   RICH IN LOW-LEVEL MOISTURE COMPARED TO FARTHER W.  ALTHOUGH
   CONVERGENCE ON SCALE OF AVAILABLE OBS APPEARS WEAK...GIVEN ONLY 5-10
   KT SFC FLOW AT MOST SITES...EXPECT ISOLATED THEN WIDELY SCATTERED
   TSTM DEVELOPMENT FROM COMBINATION OF
   1. WEAKENING MLCINH...PER MODIFIED MHX RAOB AND RUC SOUNDINGS...AND
   2. LOCALIZED/SUB-OBSERVATIONAL SCALE SOURCES OF LOW-LEVEL LIFT INVOF
   SEA BREEZES AND HORIZONTAL CONVECTIVE ROLLS.
   THIS EARLY CONVECTION INITIALLY SHOULD RESIDE E OF MOST FAVORABLE
   SHEAR...THOUGH ISOLATED...PRECIP LOADING-DRIVEN DOWNBURST NEAR SVR
   LEVELS CANNOT BE RULED OUT.
   
   POTENTIAL FOR TSTMS ALSO WILL INCREASE IN SECOND AND SOMEWHAT
   OVERLAPPING  PHASE AROUND 19Z-22Z OVER PIEDMONT REGION AS LEADING
   EDGE OF DCVA PLUME IMPINGES ON WARM SECTOR AND STEEPENS LOW-MIDLEVEL
   LAPSE RATES.  STRONGEST MIDLEVEL ASCENT CURRENTLY IS BEHIND DIFFUSE
   SFC COLD FRONT THAT IS ANALYZED FROM CENTRAL MD SWWD OVER W-CENTRAL
   NC AND W-CENTRAL SC.  HOWEVER...CONTINUED SFC HEATING AND WEAKENING
   CINH WILL RESULT IN SWATH OF MLCAPE 1000-1500 J/KG JUST E OF COLD
   FRONT OVER CENTRAL NC AND 1500-2000 J/KG NEAR COAST...DECREASING
   NEWD INTO SERN VA BUT STILL BECOMING FAVORABLE FOR TSTMS.  ALTHOUGH
   LOW-LEVEL HODOGRAPHS AND SHEAR WILL REMAIN SMALL...35-45 KT
   EFFECTIVE SHEAR MAGNITUDES--DRIVEN MAINLY BY SPEED SHEAR--WILL
   SUPPORT TSTM ORGANIZATION.
   
   ..EDWARDS.. 09/30/2011
   
   
   ATTN...WFO...AKQ...MHX...RAH...ILM...RNK...
   
   LAT...LON   34347761 34197814 34417905 34847978 35407993 36637863
               37457718 36877612 36037565 35497580 34917641 34347761