MESOSCALE DISCUSSION 1431
   NWS STORM PREDICTION CENTER NORMAN OK
   1219 PM CDT TUE JUN 28 2011
   
   AREAS AFFECTED...WRN/CNTRL NY...WRN/CNTRL PA...FAR NRN WV...E-CNTRL
   OH
   
   CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 
   
   VALID 281719Z - 281845Z
   
   THE THREAT FOR SVR STORMS IS INCREASING ACROSS PORTIONS OF THE LOWER
   GREAT LAKES AND NERN STATES...AND THE ISSUANCE OF A SVR TSTM WATCH
   IS POSSIBLE.
   
   LINES OF BUILDING CUMULUS AND DEEPENING CONVECTION ARE DEVELOPING
   ALONG BANDS OF PREFRONTAL CONVERGENCE IN ADVANCE OF A SFC COLD FRONT
   DRAPED ACROSS THE LOWER GREAT LAKES AND OHIO VALLEY REGION. A
   WELL-DEFINED PREFRONTAL TROUGH EXTENDS FROM NWRN PA INTO S-CNTRL
   OHIO. AHEAD OF THIS FEATURE...MODEST DIABATIC HEATING /SUPPORTING
   TEMPERATURES IN THE UPPER 70S TO MIDDLE 80S/ AMIDST RELATIVELY RICH
   BOUNDARY-LAYER MOISTURE /LOWEST 100-MB MEAN MIXING RATIOS OF 14.0 TO
   14.5 G PER KG ACCORDING TO OBSERVED 12Z SOUNDINGS/ HAVE RESULTED IN
   MLCAPE VALUES FROM 500 TO 1000 J/KG WITHIN A BROAD CORRIDOR
   EXTENDING TOWARD A WARM FRONT DRAPED ACROSS PARTS OF ERN NY. DESPITE
   RELATIVELY WEAK MID-LEVEL LAPSE RATES...CONTINUED PREFRONTAL
   INSOLATION WILL SUPPORT BUILDING INSTABILITY AND CONTINUED
   DEVELOPMENT/INTENSIFICATION OF CONVECTION. ENHANCED SWLY TO WSWLY
   FLOW OVER THE SERN PERIPHERY OF AN APPROACHING POTENTIAL VORTICITY
   MAXIMUM PER AREA VWP DATA WILL SUPPORT EFFECTIVE BULK SHEAR
   MAGNITUDES OF 25 TO 35...YIELDING LINEAR CONVECTIVE SEGMENTS GIVEN
   MAINLY UNIDIRECTIONAL WIND PROFILES. DMGG WIND GUSTS AND LARGE HAIL
   WILL BE THE PRIMARY THREATS WITH THESE STORMS...WITH THE GREATEST
   THREAT ACROSS PORTIONS OF CNTRL PA INTO CNTRL NY WHERE THE LARGEST
   MID-LEVEL HEIGHT FALLS WILL BE MOST STRONGLY JUXTAPOSED WITH THE
   GREATEST INSTABILITY.
   
   ..COHEN.. 06/28/2011
   
   
   ATTN...WFO...BTV...ALY...BGM...BUF...CTP...PBZ...CLE...
   
   LAT...LON   42607484 41367582 40007753 39797969 39918055 40398096
               40908085 41408042 42247977 43287875 44207710 44687547
               44217443 43547436 42607484