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211 

WWUS20 KWNS 232240

SEL9

SPC WW 232240

ARZ000-ILZ000-KYZ000-MOZ000-240500-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 189

NWS STORM PREDICTION CENTER NORMAN OK

540 PM CDT SAT APR 23 2011



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       A LARGE PART OF NORTHERN ARKANSAS

       PARTS OF SOUTHERN ILLINOIS

       PARTS OF WESTERN KENTUCKY

       PARTS OF SOUTHERN MISSOURI



EFFECTIVE THIS SATURDAY AFTERNOON FROM 540 PM UNTIL MIDNIGHT 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 50

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

SOUTHWEST OF FORT SMITH ARKANSAS TO 45 MILES EAST OF CAPE

GIRARDEAU MISSOURI.  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 186...WW 187...WW 188...



DISCUSSION...THUNDERSTORMS ARE INCREASING ALONG AND N OF STATIONARY

BOUNDARY ACROSS THE NORTHERN PORTION OF THE WATCH.  WITH 50 KT OF

SHEAR COUPLED WITH MLCAPES AOA 2000 J/KG AND STEEP MID LEVEL LAPSE

RATES...SUPERCELLS ARE LIKELY.  PRIMARY THREAT WILL BE LARGE HAIL

AND DAMAGING WINDS...PARTICULARLY WITH BOWING SEGMENTS.  ISOLATED

TORNADOES ARE ALSO POSSIBLE WITH THE SUPERCELLS...EVEN WITH RATHER

WEAK BOUNDARY LAYER 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 24035.





...HALES

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