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URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 286

NWS STORM PREDICTION CENTER NORMAN OK

530 PM CDT SUN MAY 20 2012



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       NORTHWEST TEXAS



EFFECTIVE THIS SUNDAY AFTERNOON AND EVENING FROM 530 PM UNTIL

1100 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 40

STATUTE MILES EITHER SIDE OF A LINE FROM 160 MILES WEST SOUTHWEST

OF WICHITA FALLS TEXAS TO 35 MILES SOUTH SOUTHEAST OF WICHITA

FALLS 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 285...



DISCUSSION...DESPITE THE ABSENCE OF ANY APPRECIABLE LARGE-SCALE

FORCING FOR ASCENT...DAYTIME HEATING AND CONVERGENCE ALONG AN

OUTFLOW-REINFORCED COLD FRONT APPEARS TO BE SUFFICIENT TO INITIATE

MULTIPLE TSTMS ACROSS THE WATCH AREA.  PROXIMITY FORECAST SOUNDINGS

AND JAYTON TX PROFILER INDICATE THAT AMBIENT AIR MASS IS

CHARACTERIZED BY STEEP LAPSE RATES...MLCAPE OF AROUND 1500 J/KG

WHICH IS COLLOCATED WITH A WIND PROFILE EXHIBITING PRONOUNCED

VEERING WITH HEIGHT AND RESULTING 35-40 KT OF DEEP-LAYER SHEAR.  AS

SUCH...IT APPEARS THAT THE POTENTIAL WILL EXIST FOR THE EVOLUTION OF

SUPERCELL STRUCTURES WITH AN ASSOCIATED RISK FOR LARGE HAIL.



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 34010.





...MEAD

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