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622 

WWUS20 KWNS 280804

SEL9

SPC WW 280804

DEZ000-MDZ000-NJZ000-NYZ000-PAZ000-CWZ000-281400-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 249

NWS STORM PREDICTION CENTER NORMAN OK

405 AM EDT THU APR 28 2011



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       DELAWARE

       NORTHEAST MARYLAND

       WEST AND SOUTHWEST NEW JERSEY

       PARTS OF CENTRAL INTO SOUTHEAST NEW YORK

       EASTERN PENNSYLVANIA

       COASTAL WATERS



EFFECTIVE THIS THURSDAY MORNING FROM 405 AM UNTIL 1000 AM 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 50

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

UTICA NEW YORK TO 30 MILES SOUTHWEST OF DOVER DELAWARE.  FOR A

COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE

UPDATE (WOUS64 KWNS WOU9).



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...THIS SEVERE THUNDERSTORM WATCH REPLACES

SEVERE THUNDERSTORM WATCH NUMBER 244. WATCH NUMBER 244 WILL NOT

BE IN EFFECT AFTER 405 AM EDT. CONTINUE...WW 246...WW 247...WW

248...



DISCUSSION...BROKEN BAND OF PRE-FRONTAL CONVECTION WILL PERSIST

THROUGH THE MORNING ACROSS ERN PA INTO NY IN ADVANCE OF A STRONG

MIDLEVEL TROUGH PIVOTING NEWD OVER THE OH VALLEY.  STRONG WIND

PROFILES WILL REMAIN IN PLACE ACROSS THE WATCH AREA...WHILE SURFACE

TEMPERATURES AOA 70 F AND DEWPOINTS IN THE MID-UPPER 60S WILL

MAINTAIN SURFACE-BASED INSTABILITY.  DAMAGING WINDS WILL BE THE

PRIMARY THREAT WILL EMBEDDED BOWS...THOUGH AN ISOLATED TORNADO

CANNOT BE RULED OUT WITH EMBEDDED CIRCULATIONS.



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 22045.





...THOMPSON

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