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URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 366

NWS STORM PREDICTION CENTER NORMAN OK

100 PM CDT MON JUN 21 2010



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       LARGE PART OF CENTRAL ILLINOIS

       PARTS OF CENTRAL AND EASTERN MISSOURI



EFFECTIVE THIS MONDAY AFTERNOON AND EVENING FROM 100 PM UNTIL 700

PM CDT.



HAIL TO 2 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 70

STATUTE MILES NORTH AND SOUTH OF A LINE FROM 35 MILES WEST

NORTHWEST OF KNOB NOSTER MISSOURI TO 20 MILES SOUTH SOUTHEAST OF

DECATUR ILLINOIS.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU6).



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...ALONG AND S OF OUTFLOW BOUNDARY THAT EXTENDS FROM NEAR

IRK TO MKC AIR MASS IS NOW VERY UNSTABLE WITH MLCAPES AOA 3000 J/KG.

 WITH 3OKT OF SHEAR AND RATHER STEEP LOW/MID LEVEL LAPSE RATES

THUNDERSTORMS EXPECTED TO INCREASE IN BOTH NUMBER AND INTENSITY

ACROSS THE WATCH WITH FURTHER DAYTIME HEATING.  PRIMARY THREAT WILL

BE LARGE HAIL AND DAMAGING WINDS WHICH COULD BECOME MORE WIDESPREAD

AS STORMS DEVELOP UPSCALE INTO SMALL BOW/LINE SEGMENTS.



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

TO 2 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60

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

MOTION VECTOR 27025.





...HALES

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