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WWUS20 KWNS 231459

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URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 339

NWS STORM PREDICTION CENTER NORMAN OK

1000 AM CDT MON MAY 23 2011



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       NORTH-CENTRAL TEXAS



EFFECTIVE THIS MONDAY MORNING AND AFTERNOON FROM 1000 AM UNTIL

500 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 15 MILES EAST OF

SHERMAN TEXAS TO 65 MILES WEST SOUTHWEST OF CORSICANA TEXAS.  FOR

A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH

OUTLINE UPDATE (WOUS64 KWNS WOU9).



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 337...WW 338...



DISCUSSION...ELEVATED TSTMS HAVE RAPIDLY DEVELOPED W OF THE

DALLAS-FT. WORTH AREA APPARENTLY IN CONJUNCTION WITH A MIDLEVEL

IMPULSE TRANSLATING ACROSS THE AREA.  12Z FWD SOUNDING SUGGESTS THAT

THIS ACTIVITY IS LIKELY ROOTED ABOVE THE CAP WITHIN AN ENVIRONMENT

CHARACTERIZED BY MUCAPE OF 3000-3500 J/KG AND AROUND 30 KT OF

EFFECTIVE BULK SHEAR.  THE PRIMARY HAZARD WITH THE STORMS WILL BE

LARGE HAIL.



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 28020.





...MEAD

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