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000 

WWUS20 KWNS 271728

SEL6

SPC WW 271728

DCZ000-MDZ000-VAZ000-WVZ000-CWZ000-280000-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 556

NWS STORM PREDICTION CENTER NORMAN OK

125 PM EDT FRI JUL 27 2007



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       DISTRICT OF COLUMBIA

       NORTHERN MARYLAND

       NORTHERN AND WESTERN VIRGINIA

       WEST VIRGINIA PANHANDLE

       COASTAL WATERS



EFFECTIVE THIS FRIDAY AFTERNOON AND EVENING FROM 125 PM UNTIL 800

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 75

STATUTE MILES EAST AND WEST OF A LINE FROM 40 MILES NORTHWEST OF

BALTIMORE MARYLAND TO 40 MILES SOUTH SOUTHEAST OF DUBLIN

VIRGINIA.  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 555...



DISCUSSION...THUNDERSTORMS SHOULD INCREASE IN COVERAGE AND INTENSITY

ACROSS THE REGION THIS AFTERNOON AS SERIES OF WEAK MID LEVEL

DISTURBANCES ROTATE THROUGH SRN PERIPHERY OF LARGER SCALE UPPER LOW

OVER THE EASTERN GREAT LAKES. SUSTAINED ASCENT ACROSS VERY

WARM/MOIST AND UNSTABLE AIR MASS SHOULD PROMOTE ROBUST CONVECTION.

DEEP LAYER WLY FLOW WILL SUPPORT WIND DAMAGE POTENTIAL AS STORM

MERGERS AND UPSCALE GROWTH OCCUR. MARGINAL SEVERE HAIL WILL ALSO BE

POSSIBLE WITH A FEW OF THE MORE INTENSE UPDRAFTS.



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 28020.





...CARBIN/IMY

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