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URGENT - IMMEDIATE BROADCAST REQUESTED

TORNADO WATCH NUMBER 741

NWS STORM PREDICTION CENTER NORMAN OK

915 AM CST THU DEC 20 2007



THE NWS STORM PREDICTION CENTER HAS ISSUED A

TORNADO WATCH FOR PORTIONS OF



       SOUTHERN LOUISIANA

       FAR SOUTHERN MISSISSIPPI

       COASTAL WATERS



EFFECTIVE THIS THURSDAY MORNING AND AFTERNOON FROM 915 AM UNTIL

400 PM CST.



TORNADOES...HAIL TO 1 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 70 STATUTE

MILES NORTH AND SOUTH OF A LINE FROM 45 MILES SOUTHWEST OF LAKE

CHARLES LOUISIANA TO 30 MILES EAST SOUTHEAST OF SLIDELL

LOUISIANA.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU1).



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.



DISCUSSION...UPPER TROUGH MOVING THROUGH AREA WILL MAINTAIN

THUNDERSTORMS ACROSS THE WATCH AREA INTO THE AFTERNOON HOURS.

DESPITE STORMS CURRENTLY BEING SLIGHTLY ELEVATED...SOME WARMING MAY

RESULT IN SOME STORMS BECOMING SURFACE BASED BY LATE MORNING.

INCREASING WLY WINDS ALOFT...PER 55 KT 1-2 KM ABOVE THE SURFACE AT

POE...INDICATE A  THREAT FOR WIND DAMAGE INTO THE AFTERNOON HOURS.

INSTABILITY WILL NOT BE PARTICULARLY STRONG...SBCAPES AROUND 500

J/KG...BUT WEAK SURFACE BOUNDARY FROM LCH TO SOUTH OF MSY AND STRONG

LOW/DEEP SHEAR MAY BE SUPPORTIVE OF AN ISOLATED TORNADO OR TWO.



AVIATION...TORNADOES AND 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 400.

MEAN STORM MOTION VECTOR 25045.





...IMY

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