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WWUS20 KWNS 250738

SEL1

SPC WW 250738

LAZ000-TXZ000-251500-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 691

NWS STORM PREDICTION CENTER NORMAN OK

140 AM CST TUE DEC 25 2012



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       WESTERN LOUISIANA

       CENTRAL AND EASTERN TEXAS



EFFECTIVE THIS TUESDAY MORNING FROM 140 AM UNTIL 900 AM CST.



HAIL TO 2 INCHES 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 NORTH AND SOUTH OF A LINE FROM 25 MILES WEST OF

TEMPLE TEXAS TO 20 MILES EAST OF FORT POLK LOUISIANA.  FOR A

COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE

UPDATE (WOUS64 KWNS WOU1).



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...ELEVATED TSTMS ARE EXPECTED TO INCREASE IN COVERAGE AND

INTENSITY EARLY THIS MORNING AS LARGE-SCALE FORCING FOR ASCENT

STRENGTHENS AHEAD OF AMPLIFYING SRN HIGH PLAINS SHORTWAVE TROUGH.

STEEPENING MIDLEVEL LAPSE RATES FROM THE W WILL COINCIDE WITH A

MOISTENING LOW-LEVEL AIR MASS TO PROMOTE MUCAPE VALUES OF 1000-1500

J/KG.  WHEN COUPLED WITH 40-50 KT OF EFFECTIVE BULK SHEAR...THE

ENVIRONMENT WILL FAVOR SUPERCELLS CAPABLE OF LARGE HAIL.



AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT

TO 2 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60

KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500. MEAN STORM

MOTION VECTOR 24035.





...MEAD

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