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829 

WWUS20 KWNS 211806

SEL6

SPC WW 211806

MDZ000-NCZ000-VAZ000-CWZ000-220100-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 796

NWS STORM PREDICTION CENTER NORMAN OK

210 PM EDT SUN AUG 21 2011



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       SOUTHERN MARYLAND

       NORTHERN NORTH CAROLINA

       CENTRAL AND EASTERN VIRGINIA

       COASTAL WATERS



EFFECTIVE THIS SUNDAY AFTERNOON AND EVENING FROM 210 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 120

STATUTE MILES EAST AND WEST OF A LINE FROM 45 MILES NORTH

NORTHEAST OF RICHMOND VIRGINIA TO 20 MILES WEST SOUTHWEST OF

RALEIGH NORTH CAROLINA.  FOR A COMPLETE DEPICTION OF THE WATCH

SEE THE ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU6).



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 794...WW 795...



DISCUSSION...THUNDERSTORM DEVELOPMENT IS UNDERWAY IN THE LEE OF THE

APPALACHIANS AS A SPEED MAX CROSSES THE MOUNTAINS...AND STRONG

SURFACE HEATING CONTINUES DOWNSTREAM ACROSS VA/NC.  THIS CONVECTION

WILL LIKELY INCREASE IN COVERAGE THROUGH THE AFTERNOON WITH AN

ATTENDANT RISK FOR DAMAGING WINDS AND LARGE HAIL.  OTHER MORE

ISOLATED STORMS WILL ALSO CONTINUE TO DEVELOP IN THE WARM SECTOR

ACROSS CENTRAL NC INTO SE VA.  VERTICAL SHEAR WILL BE STRONGEST

FARTHER N INTO VA...WHERE SOME SUPERCELL STRUCTURES WILL BE POSSIBLE

THIS AFTERNOON.



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 550. MEAN STORM

MOTION VECTOR 27025.





...THOMPSON

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