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682 

WWUS20 KWNS 081753

SEL8

SPC WW 081753

MDZ000-NCZ000-VAZ000-CWZ000-090200-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 638

NWS STORM PREDICTION CENTER NORMAN OK

155 PM EDT SAT SEP 8 2012



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       LOWER MARYLAND

       MUCH OF CENTRAL NORTH CAROLINA

       MUCH OF CENTRAL VIRGINIA

       COASTAL WATERS



EFFECTIVE THIS SATURDAY AFTERNOON AND EVENING FROM 155 PM UNTIL

1000 PM EDT.



HAIL TO 1 INCH 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 95

STATUTE MILES EAST AND WEST OF A LINE FROM 55 MILES NORTH OF

RICHMOND VIRGINIA TO 30 MILES EAST SOUTHEAST OF CHARLOTTE NORTH

CAROLINA.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU8).



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 634...WW 635...WW

636...WW 637...



DISCUSSION...THUNDERSTORMS ARE BEGINNING TO DEVELOP ALONG A

PRE-FRONTAL TROUGH IN THE IMMEDIATE LEE OF THE APPALACHIANS ACROSS

NC/VA.  STRONG SURFACE HEATING E OF THIS TROUGH...ALONG WITH THE

APPROACH OF THE MIDLEVEL WAVE AND ASSOCIATED STRENGTHENING OF

MIDLEVEL FLOW...WILL PROMOTE A RISK FOR ORGANIZED MULTICELL

CLUSTERS/LINE SEGMENTS CAPABLE OF PRODUCING DAMAGING WINDS AND

ISOLATED LARGE HAIL.



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

TO 1 INCH. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60 KNOTS.

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

VECTOR 27025.





...THOMPSON

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