MESOSCALE DISCUSSION 1910
   NWS STORM PREDICTION CENTER NORMAN OK
   0132 PM CDT TUE AUG 18 2009
   
   AREAS AFFECTED...ERN OH...NRN WV...WRN MD/PA/NY
   
   CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY 
   
   VALID 181832Z - 182000Z
   
   ISOLATED STRONG TO SEVERE THUNDERSTORMS ARE POSSIBLE ACROSS PORTIONS
   OF ERN OH...NRN WV...AND WRN MD/PA/NY THIS AFTERNOON. DUE TO THE
   VERY MARGINAL NATURE OF THE THREAT...A WW IS NOT EXPECTED.
   
   RECENT WV IMAGERY INDICATES AN UPPER IMPULSE QUICKLY TRANSLATING
   NEWD ACROSS SRN ONTARIO AND INTO QUEBEC. LARGE SCALE ASCENT AND A
   SURFACE COLD FRONT ARE ACCOMPANYING THIS FEATURE EWD INTO THE
   REGION...AIDING IN THUNDERSTORM INITIATION AS THE BOUNDARY LAYER
   CONTINUES TO EXPERIENCE MODEST HEATING AND MOISTENING. MID LEVEL
   LAPSE RATES ARE VERY POOR /AOB 6 C PER KM/...AS INDICATED BY 12Z
   RAOBS AND CURRENT RUC SOUNDINGS. AS A RESULT...AFTERNOON MLCAPE
   VALUES WILL GENERALLY RESIDE AROUND 1500-2000 J/KG. THE AREA ALSO
   RESIDES SOUTH OF STRONGER MID/UPPER LEVEL SWLY FLOW...RESULTING IN
   WIND FIELDS THAT ARE MAINLY SUPPORTIVE OF MULTICELL STORMS AND
   PERHAPS SHORT LINE SEGMENTS. THE THREAT OF LARGE HAIL IS EXPECTED TO
   BE LOW WITH THESE STORMS DUE TO THE WEAK LAPSE RATE AND VERTICAL
   WIND SHEAR ENVIRONMENT. HOWEVER...DAMAGING DOWNBURST WINDS MAY BE
   POSSIBLE WITH THE STRONGER UPDRAFT CORES. DUE TO THE MARGINAL NATURE
   OF THIS THREAT...A WW IS NOT EXPECTED.
   
   ..GARNER.. 08/18/2009
   
   
   ATTN...WFO...BTV...ALY...BGM...BUF...CTP...LWX...PBZ...RLX...
   CLE...
   
   LAT...LON   40758190 42927904 44987539 44977370 44167346 41677599
               39537842 39358013 39608182 40758190