

073 

WWUS20 KWNS 061750

SEL6

SPC WW 061750

LAZ000-TXZ000-CWZ000-070100-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 666

NWS STORM PREDICTION CENTER NORMAN OK

1250 PM CDT THU AUG 6 2009



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       NORTHERN AND SOUTHWEST LOUISIANA

       EASTERN TEXAS

       COASTAL WATERS



EFFECTIVE THIS THURSDAY AFTERNOON AND EVENING FROM 1250 PM UNTIL

800 PM 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 105

STATUTE MILES EITHER SIDE OF A LINE FROM 75 MILES SOUTH OF

LONGVIEW TEXAS TO 55 MILES EAST SOUTHEAST OF NATCHITOCHES

LOUISIANA.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU6).



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...CONVECTIVE CLUSTER OVER NERN LA IS EXPECTED TO CONTINUE

MOVING SWWD THIS AFTERNOON INTO A VERY MOIST AND UNSTABLE AIR MASS

WITH MLCAPE OF 2500-3000 J/KG.  LATEST WIND PROFILER AND VAD DATA

INDICATE NORTHERLY WINDS ALOFT IN THE MID/UPPER LEVELS EXCEEDING 50

KT ABOVE 300 MB.  THIS WILL PROVIDE SUFFICIENT DEEP LAYER SHEAR TO

ENHANCE STORM ORGANIZATION AND FAVORABLE STEERING FLOW FOR STORMS TO

DEVELOP/SPREAD SSWWD THIS AFTERNOON.  THERE IS POTENTIAL FOR A COLD

POOL TO INTENSIFY...AND IF THIS OCCURS DAMAGING WIND THREAT WILL

INCREASE ALONG THE LEADING EDGE OF THE COMBINED OUTFLOW BOUNDARY.



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 600. MEAN STORM

MOTION VECTOR 36020.





...WEISS

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