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282 

WWUS20 KWNS 200358

SEL7

SPC WW 200358

LAZ000-TXZ000-200900-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 687

NWS STORM PREDICTION CENTER NORMAN OK

955 PM CST WED DEC 19 2012



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       EXTREME NORTHWEST LOUISIANA

       NORTHEAST TEXAS



EFFECTIVE THIS WEDNESDAY NIGHT AND THURSDAY MORNING FROM 955 PM

UNTIL 300 AM CST.



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 80

STATUTE MILES EAST AND WEST OF A LINE FROM 65 MILES NORTH OF

LONGVIEW TEXAS TO 55 MILES SOUTH OF TYLER TEXAS.  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.



OTHER WATCH INFORMATION...CONTINUE...WW 686...



DISCUSSION...THUNDERSTORMS ARE DEVELOPING SWD ALONG A DRY LINE AS A

COLD FRONT ACCELERATES EWD AND OVERTAKES THE DRY LINE OVER NORTH

CENTRAL TX.  ALTHOUGH THE AIR MASS IS ONLY MODESTLY UNSTABLE...

STRONG WIND ALOFT/VERTICAL SHEAR WILL FAVOR OCCASIONAL SMALL

EMBEDDED BOWING SEGMENTS WITH A THREAT FOR PRIMARILY DAMAGING WIND

GUSTS AS THE STORMS CONTINUE EWD INTO THE OVERNIGHT HOURS.



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 450. MEAN STORM MOTION

VECTOR 24040.





...WEISS

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