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527 

WWUS20 KWNS 141830

SEL3

SPC WW 141830

DCZ000-MDZ000-OHZ000-PAZ000-VAZ000-WVZ000-CWZ000-150100-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 173

NWS STORM PREDICTION CENTER NORMAN OK

230 PM EDT FRI MAY 14 2010



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       DISTRICT OF COLUMBIA

       MUCH OF MARYLAND

       PARTS OF SOUTHEAST OHIO

       MUCH OF SOUTHERN PENNSYLVANIA

       NORTHERN VIRGINIA

       MUCH OF WEST VIRGINIA

       COASTAL WATERS



EFFECTIVE THIS FRIDAY AFTERNOON AND EVENING FROM 230 PM UNTIL 900

PM EDT.



HAIL TO 2.5 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 80

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



THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 90

STATUTE MILES NORTH AND SOUTH OF A LINE FROM 40 MILES WEST

NORTHWEST OF CHARLESTON WEST VIRGINIA TO 45 MILES SOUTHEAST OF

HARRISBURG 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.



OTHER WATCH INFORMATION...CONTINUE...WW 170...WW 171...WW 172...



DISCUSSION...THUNDERSTORMS ARE EXPECTED TO INCREASE IN NUMBER AND

INTENSITY ACROSS THE WATCH THRU THE AFTERNOON AS AIR MASS HAS BECOME

MODERATELY UNSTABLE.40-50KT OF SHEAR COUPLED WITH MID LEVEL LAPSE

RATES OF 7C/KM SUPPORT BOTH LARGE HAIL AND DAMAGING WINDS.  GREATEST

WIND THREAT WILL BE WITH ANY LINE SEGMENT/BOW ECHOES THAT DEVELOP IN

THE STRONG FLOW ALOFT.



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

TO 2.5 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 70

KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 550. MEAN STORM

MOTION VECTOR 26035.





...HALES

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