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358 

WWUS20 KWNS 041241

SEL5

SPC WW 041241

ILZ000-041800-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 655

NWS STORM PREDICTION CENTER NORMAN OK

740 AM CDT TUE AUG 4 2009



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       CENTRAL ILLINOIS



EFFECTIVE THIS TUESDAY MORNING AND AFTERNOON FROM 740 AM UNTIL

100 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 60

STATUTE MILES NORTH AND SOUTH OF A LINE FROM 50 MILES WEST

NORTHWEST OF SPRINGFIELD ILLINOIS TO 30 MILES SOUTH OF DANVILLE

ILLINOIS.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU5).



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 654...



DISCUSSION...STORMS WILL LIKELY CONTINUE DEVELOPING EWD ALONG

CONVECTIVE OUTFLOW BOUNDARY WHERE THE 12Z LINCOLN IL RAOB INDICATES

5000 J/KG MLCAPE...STEEP LAPSE RATES AND ONLY MODEST CONVECTIVE

INHIBITION. UNIDIRECTIONAL WLY BULK SHEAR OF 30-35 KT WILL SUPPORT

POTENTIAL FOR EMBEDDED ORGANIZED STORM STRUCTURES WITH DAMAGING WIND

AND LARGE HAIL THE MAIN THREATS.



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 500. MEAN STORM

MOTION VECTOR 25035.





...DIAL

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