

738 

WWUS20 KWNS 130143

SEL2

SPC WW 130143

OKZ000-TXZ000-130500-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 292

NWS STORM PREDICTION CENTER NORMAN OK

845 PM CDT TUE MAY 12 2009



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       SOUTHWEST OKLAHOMA

       EXTREME NORTHWEST TEXAS



EFFECTIVE THIS TUESDAY NIGHT FROM 845 PM UNTIL MIDNIGHT 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 40

STATUTE MILES EAST AND WEST OF A LINE FROM 35 MILES NORTH OF

ALTUS OKLAHOMA TO 85 MILES SOUTH OF ALTUS OKLAHOMA.  FOR A

COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE

UPDATE (WOUS64 KWNS WOU2).



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 289...WW 290...WW 291...



DISCUSSION...MERGING RIGHT AND LEFT MOVING THUNDERSTORM CLUSTERS MAY

SUPPORT UPSCALE GROWTH INTO A SMALL MCS NEAR THE RED RIVER IN THE

NEXT COUPLE OF HOURS.  THOUGH THE CAP STRENGTHENS WITH EWD

EXTENT...RESIDUAL STEEP LAPSE RATES AND STRONG INSTABILITY WILL

SUPPORT A THREAT FOR ADDITIONAL SEVERE STORM DEVELOPMENT WITH THE

STORM MERGERS.  DAMAGING WINDS /INCLUDING THE POSSIBILITY OF HEAT

BURSTS/ AND LARGE HAIL WILL BE THE MAIN SEVERE THREATS BEFORE THE

STORM WEAKEN IN A FEW HOURS.



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 27020.





...THOMPSON

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