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571 

WWUS20 KWNS 121937

SEL7

SPC WW 121937

FLZ000-CWZ000-130300-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 17

NWS STORM PREDICTION CENTER NORMAN OK

235 PM EST FRI FEB 12 2010



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       MUCH OF SOUTHERN FLORIDA

       COASTAL WATERS



EFFECTIVE THIS FRIDAY AFTERNOON AND EVENING FROM 235 PM UNTIL

1000 PM EST.



HAIL TO 0.5 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 70

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

SOUTHWEST OF KEY WEST FLORIDA TO 40 MILES NORTHEAST OF MELBOURNE

FLORIDA.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU7).



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.



DISCUSSION...VERY STRONG TROUGH/WIND FIELDS AND DEEPENING SURFACE

LOW WILL MOVE EWD ACROSS FL PENINSULA THRU THIS EVENING.  WHILE

INSTABILITY IS LIMITED...COMBINATION OF 50-60KT LLJ/80-100KT MID

LEVEL JET AND FRONTAL CONVERGENCE WILL LEAD TO A SQUALL LINE MOVING

RAPIDLY EWD ACROSS SRN PENINSULA.  DAMAGING WINDS WILL BE PRIMARY

THREAT AS LINE MOVES THRU BUT BRIEF TORNADOS AND/OR WATERSPOUTS

COULD OCCUR GIVEN THE AVAILABLE SHEAR.



AVIATION...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 26045.





...HALES

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