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WWUS20 KWNS 282256

SEL8

SPC WW 282256

LAZ000-TXZ000-CWZ000-290500-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 858

NWS STORM PREDICTION CENTER NORMAN OK

550 PM CDT WED SEP 28 2011



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       WESTERN AND SOUTHERN LOUISIANA

       SOUTHEAST TEXAS

       COASTAL WATERS



EFFECTIVE THIS WEDNESDAY AFTERNOON FROM 550 PM UNTIL MIDNIGHT CDT.



HAIL TO 1.5 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 70 MILES WEST OF

FORT POLK LOUISIANA TO 30 MILES EAST OF LAFAYETTE LOUISIANA.  FOR

A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH

OUTLINE UPDATE (WOUS64 KWNS WOU8).



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 857...



DISCUSSION...TSTMS ARE BEGINNING TO FORM ALONG WNW/ESE COLD

FRONT...AND ALONG SIMILARLY ORIENTED PREFRONTAL CONFLUENCE

LINE...NEAR THE SABINE RVR IN FAR E TX AND OVER CNTRL LA.  THE

STORMS APPEAR TO BE FORMING IN RESPONSE TO DAYTIME HEATING...AND

POSSIBLY IN RESPONSE TO INCREASING ASCENT WITH ESE-MOVING ARKLATEX

UPR VORT.  COMBINATION OF MODEST WIND FIELD WITH RELATIVELY COOL MID

LVL TEMPS /AROUND MINUS 10C AT 500 MB/...VERY WARM /90S F/ SFC

TEMPS...AND AMPLE MOISTURE SUGGESTS SOME POTENTIAL FOR SCTD DMGG

WIND GUSTS AND POSSIBLY SVR HAIL.  DEVELOPMENT OF ONE OR TWO SMALL

CLUSTERS ALSO MAY OCCUR BY MID EVE...WITH EMBEDDED LOCALIZED BOWING

SEGMENTS.



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

TO 1.5 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60

KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 550. MEAN STORM

MOTION VECTOR 30020.





...CORFIDI

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