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WWUS20 KWNS 041925

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SPC WW 041925

LAZ000-TXZ000-050300-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 345

NWS STORM PREDICTION CENTER NORMAN OK

225 PM CDT MON JUN 4 2007



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       SOUTHWEST LOUISIANA

       CENTRAL AND SOUTHEAST TEXAS



EFFECTIVE THIS MONDAY AFTERNOON AND EVENING FROM 225 PM UNTIL

1000 PM CDT.



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 55

STATUTE MILES NORTH AND SOUTH OF A LINE FROM 75 MILES WEST OF

AUSTIN TEXAS TO 15 MILES EAST NORTHEAST OF LAKE CHARLES

LOUISIANA.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU5).



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...SCATTERED THUNDERSTORMS ARE DEVELOPING ALONG A DIFFUSE

SURFACE BOUNDARY FROM THE HILL COUNTRY EWD INTO SE TX.  MODERATE

INSTABILITY IS PRESENT ALONG AND S OF THIS BOUNDARY...WHILE DEEP

LAYER SPEED SHEAR IS SUFFICIENT FOR A FEW SUPERCELLS IN THE BELT OF

STRONGER FLOW S OF AN MCV OVER N TX.  LARGE HAIL WILL BE THE MAIN

THREAT INITIALLY...AND DAMAGING WINDS MAY ALSO BECOME A THREAT AS

STORMS MERGE AND GROW INTO LARGER CLUSTERS LATER THIS AFTERNOON.



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 30020.





...THOMPSON

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