Severe Thunderstorm Watch 794

Tornadoes

Probability of 2 or more tornadoes	Low (20%)
Probability of 1 or more strong (F2-F5) tornadoes	Low (5%)

Wind

Probability of 10 or more severe wind events	High (80%)
Probability of 1 or more wind events > 65 knots	Mod (40%)

Hail

Probability of 10 or more severe hail events	Mod (40%)
Probability of 1 or more hailstones > 2 inches	Low (20%)

Combined Severe Hail/Wind

Probability of 6 or more combined severe hail/wind events

High (>95%)

 URGENT - IMMEDIATE BROADCAST REQUESTED
   SEVERE THUNDERSTORM WATCH NUMBER 794
   NWS STORM PREDICTION CENTER NORMAN OK
   1255 PM EDT SUN AUG 21 2011
   
   THE NWS STORM PREDICTION CENTER HAS ISSUED A
   SEVERE THUNDERSTORM WATCH FOR PORTIONS OF 
   
          WESTERN CONNECTICUT
          DISTRICT OF COLUMBIA
          DELAWARE
          MARYLAND
          NEW JERSEY
          EXTREME SOUTHEAST NEW YORK
          CENTRAL AND EASTERN PENNSYLVANIA
          NORTHERN VIRGINIA
          THE EASTERN WEST VIRGINIA PANHANDLE
          COASTAL WATERS
   
   EFFECTIVE THIS SUNDAY AFTERNOON AND EVENING FROM 1255 PM UNTIL
   900 PM EDT.
   
   HAIL TO 2 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 90
   STATUTE MILES EAST AND WEST OF A LINE FROM 45 MILES NORTH
   NORTHEAST OF ALLENTOWN PENNSYLVANIA TO 55 MILES SOUTH SOUTHWEST
   OF WASHINGTON DISTRICT OF COLUM.  FOR A COMPLETE DEPICTION OF THE
   WATCH SEE THE ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU4).
   
   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 WILL INCREASE IN COVERAGE/INTENSITY THIS
   AFTERNOON IN CONJUNCTION WITH CONTINUED DAYTIME HEATING...AND AS A
   MIDLEVEL TROUGH AND COLD FRONT MOVE EWD/SEWD ACROSS THE REGION. 
   ADDITIONALLY...A SURFACE LEE TROUGH FROM NRN VA TO ERN PA/SE NY WILL
   HELP FOCUS THUNDERSTORM DEVELOPMENT.  MODERATE-STRONG INSTABILITY
   /MLCAPE AOA 2000 J PER KG/ AND INCREASING VERTICAL SHEAR THROUGH THE
   AFTERNOON WILL BE FAVORABLE FOR STORMS TO PRODUCE DAMAGING WINDS AND
   LARGE HAIL.  A COUPLE OF SUPERCELLS MAY ALSO DEVELOP THIS AFTERNOON
   NEAR THE LEE TROUGH...AND AN ISOLATED TORNADO WILL BE POSSIBLE WHERE
   LOW-LEVEL SHEAR WILL BE SOMEWHAT STRONGER.

-Storm Prediction Center