

454 

WWUS20 KWNS 211847

SEL6

SPC WW 211847

TXZ000-220200-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 316

NWS STORM PREDICTION CENTER NORMAN OK

145 PM CDT SAT MAY 21 2011



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       CENTRAL TEXAS



EFFECTIVE THIS SATURDAY AFTERNOON AND EVENING FROM 145 PM UNTIL

900 PM CDT.



HAIL TO 2.5 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 60

STATUTE MILES EAST AND WEST OF A LINE FROM 80 MILES WEST

SOUTHWEST OF AUSTIN TEXAS TO 50 MILES EAST NORTHEAST OF

STEPHENVILLE 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.



DISCUSSION...ISOLATED SEVERE TSTM DEVELOPMENT IS ANTICIPATED WITHIN

THE NEXT HOUR ALONG SLOW-MOVING DRYLINE.  WARM SECTOR AIR MASS IS

HOT AND QUITE MOIST WITH MLCAPE VALUES OF 2500-3500+ J/KG.  WHILE

LOW-LEVEL WIND FIELD IS NOT PARTICULARLY STRONG...THE PRESENCE OF

AROUND 40 KT WLY FLOW IN THE MIDLEVELS IS RESULTING IN SUFFICIENT

DEEP-LAYER SHEAR FOR SUPERCELLS.  VERY LARGE HAIL WILL BE THE

PRIMARY HAZARD WITH ANY STORMS THAT DEVELOP.



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

TO 2.5 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60

KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 600. MEAN STORM

MOTION VECTOR 27020.





...MEAD

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