MESOSCALE DISCUSSION 0576
   NWS STORM PREDICTION CENTER NORMAN OK
   0500 PM CDT MON APR 25 2011
   
   AREAS AFFECTED...ERN OH...MUCH OF PA
   
   CONCERNING...SEVERE THUNDERSTORM WATCH 202...
   
   VALID 252200Z - 252300Z
   
   THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 202
   CONTINUES.
   
   RECENT RADAR TRENDS INDICATE ISOLATED THUNDERSTORMS HAVE DEVELOPED
   ACROSS WRN/CNTRL PORTIONS OF THE WW...WITH SMALL BOWING SEGMENTS AND
   ROTATING STORMS OBSERVED AT TIMES. CONVECTION HAS BEEN KEPT RATHER
   DISCRETE AS UPPER RIDGE IS POSITIONED TO THE W OF THE AREA...BUT
   WEAK LOW-LEVEL CONFLUENCE AND WAA CONTINUES TO INITIATE NEW
   CONVECTION ACROSS ERN OH...MOVING NEWD INTO WRN PA. SFC FRONT HAS
   RETREATED NWD TO NEAR THE NY/PA BORDER AND NERN OH...WITH
   TEMPERATURES HEATING UP INTO THE 70S-LOWER 80S IN MUCH OF THE WARM
   SECTOR. HOWEVER...DRIER BOUNDARY LAYER CONDITIONS ARE OBSERVED
   ACROSS PORTIONS OF CNTRL PA /SFC DEW POINTS 40S-50S/...BUT THIS WILL
   LIKELY ENHANCE THE POTENTIAL FOR STRONG DOWNBURSTS CAPABLE OF
   PRODUCING DMGG WINDS. STRONG MIDLEVEL FLOW CONTINUES TO YIELD
   EFFECTIVE BULK SHEAR VALUES OF 50+ KTS...AND COMBINED WITH STEEP
   MIDLEVEL LAPSE RATES...WILL SUPPORT ROTATING UPDRAFTS INTO THE
   EVENING....AND A CONTINUING THREAT FOR LARGE HAIL AND DMGG WINDS.
   ADDITIONALLY...THE POTENTIAL FOR A TORNADO OR TWO MAY EXIST NEAR THE
   SFC FRONT...WHERE LOW-LEVEL WIND SHEAR IS ENHANCED /AROUND 150-200
   M^2 S^-2/ AND LOWER LCL HEIGHTS/ SMALLER T-TD SPREADS ARE IN PLACE.
   
   ..ROGERS.. 04/25/2011
   
   
   ATTN...WFO...BGM...BUF...CTP...PBZ...RLX...CLE...
   
   LAT...LON   39478206 41068206 42197672 40627673 39478206