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URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 243

NWS STORM PREDICTION CENTER NORMAN OK

1035 PM CDT FRI MAY 4 2012



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       WEST CENTRAL INTO SOUTHERN ILLINOIS

       EXTREME EAST CENTRAL MISSOURI



EFFECTIVE THIS FRIDAY NIGHT AND SATURDAY MORNING FROM 1035 PM

UNTIL 500 AM CDT.



HAIL TO 1.5 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 45

STATUTE MILES NORTH AND SOUTH OF A LINE FROM 60 MILES NORTHWEST

OF SAINT LOUIS MISSOURI TO 35 MILES SOUTHEAST OF MOUNT VERNON

ILLINOIS.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU3).



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 240...WW 241...



DISCUSSION...ELEVATED CONVECTION WILL INCREASE IN COVERAGE/INTENSITY

THE NEXT FEW HOURS IN ASSOCIATION WITH WAA ON THE NOSE OF A 35 KT

SWLY LLJ.  THE UPSTREAM FEED OF 2000-3000 J/KG MUCAPE AND STEEP

MIDLEVEL LAPSE RATES WILL SUPPORT A RISK FOR LARGE HAIL WITH THE

STRONGEST STORMS.  OVERNIGHT...CONVECTION WILL CONTINUE TO SPREAD

ESEWD...WITH UPSCALE GROWTH INTO A CLUSTER/ISOLATED DAMAGING WINDS

POSSIBLE.



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

TO 1.5 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60

KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500. MEAN STORM

MOTION VECTOR 30025.





...THOMPSON

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