

000 

WWUS20 KWNS 161459

SEL2

SPC WW 161459

ILZ000-162000-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 602

NWS STORM PREDICTION CENTER NORMAN OK

1000 AM CDT THU AUG 16 2007



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       CENTRAL ILLINOIS



EFFECTIVE THIS THURSDAY MORNING AND AFTERNOON FROM 1000 AM UNTIL

300 PM 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 35

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

SOUTHWEST OF SPRINGFIELD ILLINOIS TO 35 MILES SOUTHEAST OF

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

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU2).



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...A SMALL MCS HAS BECOME MORE ORGANIZED DURING THE PAST

HOUR WHILE MOVING ESEWD ACROSS THE MS RIVER INTO W CENTRAL IL.  THIS

STORM CLUSTER MAY PERSIST FOR THE NEXT FEW HOURS WHILE MOVING ALONG

THE IMMEDIATE COOL SIDE OF A BAROCLINIC ZONE ACROSS CENTRAL

IL...GIVEN MODERATE INSTABILITY AND SOMEWHAT ENHANCED LOW-MID LEVEL

FLOW JUST N OF THE BOUNDARY.  DAMAGING WINDS AND ISOLATED LARGE HAIL

WILL BE THE MAIN SEVERE THREATS.



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 28035.





...THOMPSON

