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WWUS20 KWNS 010640

SEL9

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OKZ000-TXZ000-011400-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 259

NWS STORM PREDICTION CENTER NORMAN OK

140 AM CDT SUN MAY 1 2011



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       SOUTHERN OKLAHOMA

       NORTHWEST AND NORTH CENTRAL TEXAS



EFFECTIVE THIS SUNDAY MORNING FROM 140 AM UNTIL 900 AM 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 55

STATUTE MILES NORTH AND SOUTH OF A LINE FROM 20 MILES WEST

NORTHWEST OF ABILENE TEXAS TO 40 MILES SOUTHEAST OF SHERMAN

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 257...WW 258...



DISCUSSION...ELEVATED TSTMS WITH A THREAT FOR LARGE HAIL EXPECTED TO

INCREASE IN COVERAGE THROUGH LATER THIS MORNING ACROSS WW AREA AS

ASCENT INCREASES DOWNSTREAM FROM ERN NM UPR IMPULSE.  DEEP EML ABOVE

FRONTAL SURFACE AND SEASONABLY RICH MOISTURE INFLOW /PW AROUND 1.50

INCHES/ SUGGEST POTENTIAL FOR SUSTAINED/SUPERCELLS GIVEN 50+ KT WSW

MID LVL FLOW.



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 500. MEAN STORM

MOTION VECTOR 25030.





...CORFIDI

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