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432 

WWUS20 KWNS 281854

SEL7

SPC WW 281854

ILZ000-MOZ000-290000-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 197

NWS STORM PREDICTION CENTER NORMAN OK

150 PM CDT SAT APR 28 2012



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       CENTRAL ILLINOIS

       EASTERN MISSOURI



EFFECTIVE THIS SATURDAY AFTERNOON AND EVENING FROM 150 PM UNTIL

700 PM CDT.



HAIL TO 3 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 40

STATUTE MILES NORTH AND SOUTH OF A LINE FROM 65 MILES WEST OF

SAINT LOUIS MISSOURI TO 50 MILES SOUTHEAST OF MATTOON ILLINOIS.

FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH

OUTLINE UPDATE (WOUS64 KWNS WOU7).



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...EXPECT TSTMS TO CONTINUE TO INCREASE NEAR A WEAK

SURFACE LOW AND WARM FRONT SITUATED FROM NEAR STL AREA EAST ACROSS

SCNTRL IL. MODERATELY UNSTABLE AIR MASS FUELING THIS DEVELOPMENT

WILL PROMOTE STOUT STORM UPDRAFTS AMIDST SUFFICIENT VERTICAL SHEAR

FOR SUPERCELL DEVELOPMENT AND ATTENDANT THREATS OF LARGE HAIL AND

HIGH WINDS. THERE MAY DEVELOP A MORE FOCUSED CORRIDOR ALONG THE WARM

FRONT WHERE PERSISTENT ROTATING UPDRAFTS WILL BE CAPABLE OF

GENERATING VERY LARGE/DAMAGING HAIL. IN ADDITION...LOW LEVEL FLOW

NEAR THE BOUNDARY ACROSS PORTIONS OF CNTRL/ERN IL WILL NEED TO BE

MONITORED FOR PERSISTENT BACKING THAT COULD SUPPORT A GREATER

TORNADO POTENTIAL THAN CURRENTLY ANTICIPATED. IF THIS SCENARIO

BECOMES MORE LIKELY...A TORNADO WATCH MAY BE NEEDED IN AREAS

CURRENTLY COVERED BY THE SVR TSTM WATCH.



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

TO 3 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60

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

MOTION VECTOR 28025.





...CARBIN

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