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WWUS20 KWNS 201023

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URGENT - IMMEDIATE BROADCAST REQUESTED

TORNADO WATCH NUMBER 689

NWS STORM PREDICTION CENTER NORMAN OK

425 AM CST THU DEC 20 2012



THE NWS STORM PREDICTION CENTER HAS ISSUED A

TORNADO WATCH FOR PORTIONS OF



       CENTRAL AND SOUTHERN ALABAMA

       WESTERN PANHANDLE OF FLORIDA

       SOUTHEASTERN LOUISIANA

       CENTRAL AND SOUTHERN MISSISSIPPI

       COASTAL WATERS



EFFECTIVE THIS THURSDAY MORNING FROM 425 AM UNTIL NOON CST.



TORNADOES...HAIL TO 1 INCH IN DIAMETER...THUNDERSTORM WIND GUSTS

TO 75 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.



THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 140 STATUTE

MILES EAST AND WEST OF A LINE FROM 25 MILES SOUTHWEST OF GULFPORT

MISSISSIPPI TO TUSCALOOSA ALABAMA.  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...CONVECTION IS INCREASING IN INTENSITY AND COVERAGE

WITHIN FAVORABLE ENVIRONMENT THAT IS SPREADING INLAND ACROSS WW

AREA.  EXPECT FAVORABLE JUXTAPOSITION OF NEWD-SPREADING WARM SECTOR

-- CHARACTERIZED BY 60S F SFC DEW POINTS AND LOW 70S NEAR COAST --

WITH STG KINEMATIC REGIME CHARACTERIZED BY 45-55 KT EFFECTIVE SHEAR

AND 250-450 J/KG EFFECTIVE SRH.  THIS WILL SUPPORT STORM-SCALE

ROTATION AND TORNADO POTENTIAL WITH DISCRETE CELLS...AS WELL AS

DAMAGING WIND AND SPORADIC TORNADO RISK WITH QLCS BOW/LEWP FEATURES.



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

SURFACE AND ALOFT TO 1 INCH. EXTREME TURBULENCE AND SURFACE WIND

GUSTS TO 65 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500.

MEAN STORM MOTION VECTOR 24035.





...EDWARDS

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