

929 

WWUS20 KWNS 011226

SEL0

SPC WW 011226

ARZ000-OKZ000-011900-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 220

NWS STORM PREDICTION CENTER NORMAN OK

725 AM CDT FRI MAY 1 2009



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       WESTERN ARKANSAS

       NORTHERN...CENTRAL AND EASTERN OKLAHOMA



EFFECTIVE THIS FRIDAY MORNING AND AFTERNOON FROM 725 AM UNTIL 200

PM CDT.



HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 80

MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.



THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 60

STATUTE MILES NORTH AND SOUTH OF A LINE FROM 45 MILES NORTH

NORTHWEST OF OKLAHOMA CITY OKLAHOMA TO 55 MILES EAST SOUTHEAST OF

FORT SMITH ARKANSAS.  FOR A COMPLETE DEPICTION OF THE WATCH SEE

THE ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU0).



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...STRENGTHENING COMPLEXES OF STG-SVR TSTMS -- INITIALLY

OVER N-CENTRAL AND NERN OK -- MAY BECOME STILL BETTER ORGANIZED AS

THEY MOVE INTO GRADUALLY WARMING/DESTABILIZING AIR MASS WITH MLCAPE

INCREASING TO 2000-3000 J/KG RANGE OVER MUCH OF THIS AREA...AND

WEAKENING MLCINH.  BOTH FORWARD AND REAR PROPAGATIONAL MOTION

COMPONENTS APPEAR LIKELY IN THIS SITUATION...LEADING TO THREAT FOR

DAMAGING WIND THAT WILL EXPAND SWD/SEWD WITH TIME.



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

TO 2 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 70

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

MOTION VECTOR 30030.





...EDWARDS/IMY

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