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URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 575

NWS STORM PREDICTION CENTER NORMAN OK

120 PM EDT THU AUG 5 2010



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       DISTRICT OF COLUMBIA

       CENTRAL AND SOUTHERN DELAWARE

       MARYLAND

       NORTHWEST NORTH CAROLINA

       VIRGINIA

       SOUTHEAST WEST VIRGINIA

       COASTAL WATERS



EFFECTIVE THIS THURSDAY AFTERNOON AND EVENING FROM 120 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 85

STATUTE MILES NORTH AND SOUTH OF A LINE FROM 15 MILES WEST

SOUTHWEST OF BLUEFIELD WEST VIRGINIA TO 50 MILES EAST OF PATUXENT

RIVER 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 574...



DISCUSSION...THUNDERSTORMS ARE EXPECTED TO INCREASE IN

COVERAGE/INTENSITY EARLY THIS AFTERNOON IN ADVANCE OF A SURFACE COLD

FRONT AS STRONG SURFACE HEATING CONTINUES TO DESTABILIZE THE

BOUNDARY LAYER.  MLCAPE HAS NOW INCREASED TO NEAR 3000 J/KG OVER

MUCH OF VA...IN AN ENVIRONMENT SUPPORTIVE OF ORGANIZED MULTICELL

CLUSTERS/LINE SEGMENTS ON THE SRN FRINGE OF THE STRONGER MIDLEVEL

WLY FLOW.  GIVEN THE MODERATE-STRONG INSTABILITY AND STEEP LOW-LEVEL

LAPSE RATES...DAMAGING WINDS WILL BE LIKELY WITH THE STRONGER STORMS

THROUGH LATE EVENING.



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 550. MEAN STORM

MOTION VECTOR 28030.





...THOMPSON

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