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653 

WWUS20 KWNS 301638

SEL9

SPC WW 301638

DEZ000-MDZ000-PAZ000-CWZ000-302300-



URGENT - IMMEDIATE BROADCAST REQUESTED

TORNADO WATCH NUMBER 689

NWS STORM PREDICTION CENTER NORMAN OK

1240 PM EDT THU SEP 30 2010



THE NWS STORM PREDICTION CENTER HAS ISSUED A

TORNADO WATCH FOR PORTIONS OF



       DELAWARE

       NORTHEAST MARYLAND

       SOUTHEAST PENNSYLVANIA

       COASTAL WATERS



EFFECTIVE THIS THURSDAY AFTERNOON AND EVENING FROM 1240 PM UNTIL

700 PM EDT.



TORNADOES...HAIL TO 0.5 INCH IN DIAMETER...THUNDERSTORM WIND

GUSTS TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE

AREAS.



THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 50 STATUTE

MILES EAST AND WEST OF A LINE FROM 45 MILES NORTHWEST OF

ALLENTOWN PENNSYLVANIA TO 35 MILES SOUTHEAST OF PATUXENT RIVER

MARYLAND.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU9).



REMEMBER...A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR

TORNADOES AND 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.



OTHER WATCH INFORMATION...CONTINUE...WW 688...



DISCUSSION...A BAND OF THUNDERSTORMS EXTENDS FROM THE CHESAPEAKE BAY

NORTHWARD INTO EASTERN PA.  SEVERAL OF THESE STORMS HAVE SHOWN WEAK

TO MODERATE MID/LOW LEVEL ROTATION DUE TO VERY STRONG VERTICAL SHEAR

PROFILES.  DESPITE WEAK INSTABILITY...THE RISK WITH BE PRESENT FOR

ISOLATED TORNADOES THROUGH THE AFTERNOON OVER THE WATCH AREA.



AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL

SURFACE AND ALOFT TO 0.5 INCH. EXTREME TURBULENCE AND SURFACE

WIND GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO

400. MEAN STORM MOTION VECTOR 21040.





...HART

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