

017 

WWUS20 KWNS 031948

SEL3

SPC WW 031948

MDZ000-PAZ000-VAZ000-WVZ000-040200-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 263

NWS STORM PREDICTION CENTER NORMAN OK

350 PM EDT TUE MAY 3 2011



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       PARTS OF WESTERN MARYLAND

       LARGE PART OF CENTRAL AND EASTERN PENNSYLVANIA

       SMALL PART OF NORTHERN VIRGINIA

       SMALL PART OF EASTERN WEST VIRGINIA PANHANDLE



EFFECTIVE THIS TUESDAY AFTERNOON AND EVENING FROM 350 PM UNTIL

1000 PM EDT.



HAIL TO 1.5 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 70

MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.



THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 70

STATUTE MILES EAST AND WEST OF A LINE FROM 10 MILES SOUTH OF

MARTINSBURG WEST VIRGINIA TO 45 MILES NORTH OF WILKESBARRE

PENNSYLVANIA.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU3).



REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE

FAVORABLE FOR SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH

AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR

THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS

AND POSSIBLE WARNINGS. SEVERE THUNDERSTORMS CAN AND OCCASIONALLY

DO PRODUCE TORNADOES.



DISCUSSION...THUNDERSTORMS EXPECTED TO INCREASE IN NUMBER AND

INTENSITY AHEAD OF COLD FRONT AND APPROACHING SURFACE LOW.  WITH

STRONG HEATING...MLCAPES ACROSS THE WATCH RANGE UPWARDS TO 1500

J/KG...WHICH COUPLED WITH 40-50KT OF SHEAR WILL SUPPORT A FEW

THUNDERSTORMS BECOMING SEVERE WITH DAMAGING WINDS THE PRIMARY

THREAT.



AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT

TO 1.5 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60

KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500. MEAN STORM

MOTION VECTOR 23035.





...HALES

