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402 

WWUS20 KWNS 130804

SEL3

SPC WW 130804

DCZ000-MDZ000-PAZ000-VAZ000-WVZ000-CWZ000-131500-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 303

NWS STORM PREDICTION CENTER NORMAN OK

400 AM EDT THU JUN 13 2013



THE NWS STORM PREDICTION CENTER HAS ISSUED A



* SEVERE THUNDERSTORM WATCH FOR PORTIONS OF

  DISTRICT OF COLUMBIA

  WESTERN AND CENTRAL MARYLAND

  CENTRAL PENNSYLVANIA

  NORTHERN VIRGINIA

  EASTERN WEST VIRGINIA PANHANDLE

  COASTAL WATERS



* EFFECTIVE THIS THURSDAY MORNING FROM 400 AM UNTIL 1100 AM EDT.



* PRIMARY THREATS INCLUDE...

  SEVERAL DAMAGING WIND GUSTS TO 70 MPH POSSIBLE

  SEVERAL LARGE HAIL EVENTS TO 1.5 INCHES IN DIAMETER POSSIBLE

  A FEW TORNADOES POSSIBLE



THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 90

STATUTE MILES EAST AND WEST OF A LINE FROM 25 MILES WEST

NORTHWEST OF WILLIAMSPORT PENNSYLVANIA TO 40 MILES SOUTHWEST OF

WASHINGTON DISTRICT OF COLUM.  FOR A COMPLETE DEPICTION OF THE

WATCH SEE THE ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU3).



PRECAUTIONARY/PREPAREDNESS ACTIONS...



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 302...



DISCUSSION...THE NORTHERN FLANK OF A STRONG/SEVERE MESOSCALE

CONVECTIVE SYSTEM IS GENERALLY MAINTAINING STRENGTH ACROSS THE UPPER

OHIO VALLEY. ACTIVITY IS EXPECTED TO CONTINUE EASTWARD ALONG A WARM

FRONTAL ZONE ACROSS THE ALLEGHENIES THROUGH MUCH OF CENTRAL

PENNSYLVANIA BY MID MORNING...WITH A RISK FOR POTENTIALLY DAMAGING

WIND GUSTS.  WHILE THE SOUTH END OF THE CONVECTIVE SYSTEM HAS BEEN

WEAKER...POTENTIAL EXISTS FOR THE ASSOCIATED OUTFLOW BOUNDARY TO

SUPPORT NEW STRONG/SEVERE STORM DEVELOPMENT AS IT ADVANCES ACROSS

THE ALLEGHENIES AND BLUE RIDGE...INTO AN UNSTABLE ENVIRONMENT ACROSS

THE WASHINGTON D.C./BALTIMORE AREA BY 11-13Z.



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 500. MEAN STORM

MOTION VECTOR 28040.





...KERR

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