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URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 176

NWS STORM PREDICTION CENTER NORMAN OK

305 PM CDT THU APR 21 2011



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       SOUTHWEST AND WEST-CENTRAL TEXAS



EFFECTIVE THIS THURSDAY AFTERNOON AND EVENING FROM 305 PM UNTIL

1000 PM CDT.



HAIL TO 3 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 65

STATUTE MILES EAST AND WEST OF A LINE FROM 50 MILES NORTHWEST OF

ABILENE TEXAS TO 20 MILES SOUTH OF DRYDEN TEXAS.  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.



OTHER WATCH INFORMATION...CONTINUE...WW 175...



DISCUSSION...TSTMS ARE CURRENTLY DEVELOPING ALONG THE HIGH TERRAIN

OF SWRN TX AND ADDITIONAL INITIATION IS POSSIBLE LATER THIS

AFTERNOON ALONG WARM FRONT RETREATING NWD THROUGH W-CNTRL TX.  WARM

SECTOR AIR MASS IS WARM AND QUITE MOIST AND WHEN COUPLED WITH STEEP

MIDLEVEL LAPSE RATES...IS STRONGLY UNSTABLE WITH MLCAPE VALUES OF

2500-3500 J/KG.  AREA VAD/PROFILER DATA SHOW SELY LOW-LEVEL WINDS

VEERING TO SWLY IN THE MIDLEVELS WITH 30-35 KT OF DEEP WLY

SHEAR...SUFFICIENT FOR ORGANIZED/ROTATING UPDRAFTS GIVEN THE DEGREE

OF INSTABILITY.  VERY LARGE HAIL WILL BE THE PRIMARY HAZARD...THOUGH

A BRIEF TORNADO AND/OR DAMAGING WIND GUSTS WILL ALSO BE POSSIBLE.



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

TO 3 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60

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

MOTION VECTOR 29020.





...MEAD

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