MESOSCALE DISCUSSION 0815
   NWS STORM PREDICTION CENTER NORMAN OK
   0402 PM CDT THU MAY 19 2011
   
   AREAS AFFECTED...SERN-ERN PA...NJ AND PARTS OF SERN NY
   
   CONCERNING...SEVERE THUNDERSTORM WATCH 307...
   
   VALID 192102Z - 192200Z
   
   THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 307
   CONTINUES.
   
   REGIONAL RADAR IMAGERY AND OBJECTIVE ANALYSES SHOWED A CONVECTIVELY
   OVERTURNED AND COOLER AIR MASS NOW EXISTS ACROSS PARTS OF CENTRAL
   AND NORTH CENTRAL PA...RESULTING IN A DIMINISHED SEVERE WEATHER
   THREAT.  THIS TREND WOULD SUPPORT THE REMOVAL OF COUNTIES FROM THE
   NWRN PART OF WW 307.
   
   OTHERWISE...THE SRN AND ERN PARTS OF WW 307 REMAIN FAVORABLE FOR A
   FEW ADDITIONAL STRONG TO SEVERE STORMS IN THE SHORT TERM.  MID-LATE
   AFTERNOON WATER VAPOR IMAGERY SHOWED A MIDLEVEL SHORTWAVE TROUGH
   TRACKING NEWD THROUGH ERN VA/MD...LIKELY AIDING IN RECENT TSTM
   DEVELOPMENT ACROSS EAST CENTRAL VA AND INVOF BALTIMORE MD...WHILE A
   LEAD IMPULSE SUPPORTS ACTIVITY SPREADING NWD FROM ERN PA/NJ.
   
   THE PARENT CLOSED LOW HAS CONTINUED TO MOVE EWD INTO WRN PA PER
   SATELLITE IMAGERY...RESULTING IN STRONGER MIDLEVEL WINDS/SHEAR
   SHIFTING EWD OF WW 307.  ALTHOUGH FORCING FOR ASCENT WITH THE
   MIDLEVEL FEATURES SHOULD PROVE FAVORABLE IN MAINTAINING CONVECTION
   INTO THE EVENING ACROSS ERN PA/NJ INTO SERN NY...WEAKENING SHEAR AND
   INSTABILITY SHOULD SUPPORT A GRADUAL DIMINISHING TREND IN SEVERE
   WEATHER THREAT.
   
   ..PETERS.. 05/19/2011
   
   
   ATTN...WFO...OKX...ALY...PHI...BGM...CTP...LWX...
   
   LAT...LON   42787557 42827370 40767392 40117453 39607445 39587511
               39647695 40567685 41007590 42787557