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495 

WWUS20 KWNS 252039

SEL5

SPC WW 252039

DCZ000-DEZ000-MDZ000-PAZ000-VAZ000-WVZ000-CWZ000-260300-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 105

NWS STORM PREDICTION CENTER NORMAN OK

440 PM EDT SUN APR 25 2010



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       DISTRICT OF COLUMBIA

       PARTS OF DELAWARE

       MUCH OF MARYLAND

       SMALL PART OF SOUTHERN PENNSYLVANIA

       PARTS OF NORTHERN VIRGINIA

       SMALL PART OF EASTERN WEST VIRGINIA

       COASTAL WATERS



EFFECTIVE THIS SUNDAY AFTERNOON AND EVENING FROM 440 PM UNTIL

1100 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 55

STATUTE MILES NORTH AND SOUTH OF A LINE FROM 65 MILES WEST OF

MARTINSBURG WEST VIRGINIA TO 40 MILES EAST NORTHEAST OF SALISBURY

MARYLAND.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU5).



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.



OTHER WATCH INFORMATION...CONTINUE...WW 103...WW 104...



DISCUSSION...THUNDERSTORMS DEVELOPING OFF HIGHER TERRAIN NRN VA/WV

WILL MOVE EWD INTO A MDTLY UNSTABLE AIR MASS.  WITH 40-50 KT OF

SHEAR AND THE RATHER PRONOUNCED E/W FRONTAL ZONE ACROSS THE DCA

AREA...CONDITIONS WILL BE FAVORABLE FOR CLUSTERS OF STRONG/SEVERE

THUNDERSTORMS.  ADDITIONALLY A SUPERCELL COULD FORM VICINITY OF

SURFACE BOUNDARY ENHANCING BOTH THE LARGE HAIL POTENTIAL AND A BRIEF

TORNADO THREAT.



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

TO 2 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60

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

MOTION VECTOR 27030.





...HALES

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