MESOSCALE DISCUSSION 0850
   NWS STORM PREDICTION CENTER NORMAN OK
   0529 PM CDT SAT MAY 16 2009
   
   AREAS AFFECTED...CENTRAL AND ERN PA/S CENTRAL AND SERN NY/WRN NJ
   
   CONCERNING...SEVERE THUNDERSTORM WATCH 311...
   
   VALID 162229Z - 170030Z
   
   THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 311
   CONTINUES.
   
   CLUSTERS OF STRONG/LOCALLY-SEVERE STORMS CONTINUE MOVING EWD ACROSS
   WW 311.
   
   LATEST RADAR SHOWS WIDESPREAD THUNDERSTORMS MOVING EWD ACROSS PA/NY
   ATTM...WITH LOCALLY STRONG/SEVERE STORMS WITHIN A BROKEN BAND FROM
   NEAR BGM SSWWD ACROSS CENTRAL PA.  THE STORMS ARE OCCURRING
   NEAR/AHEAD OF A SURFACE TROUGH/FRONT CROSSING CENTRAL NY/WRN PA
   ATTM...AHEAD OF WHICH A MODESTLY-UNSTABLE AIRMASS PERSISTS.  
   
   SEVERE THREAT SHOULD BEGIN TO SLOWLY DIMINISH OVER THE NEXT FEW
   HOURS...AS A LOSS OF DIURNAL HEATING RESULTS IN A SLOWLY-STABILIZING
   AIRMASS.  THE SEVERE THREAT SHOULD PERSIST LONGEST ACROSS ERN PA AND
   INTO WRN NJ...WHERE THE BEST COMBINATION OF SHEAR AND INSTABILITY
   EXISTS...AND MAY LINGER INTO MUCH OF THE EVENING.  WITH STORMS
   NEARING THE ERN EDGE OF THE PA PORTION OF WW 311...AREA IS BEING
   MONITORED FOR POSSIBLE NEW WW.
   
   ..GOSS.. 05/16/2009
   
   
   ATTN...WFO...OKX...ALY...PHI...BGM...CTP...LWX...PBZ...
   
   LAT...LON   39677691 39907875 41007937 42137687 43437465 42917341
               39837444 39687565 39677691