URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 676
STORM PREDICTION CENTER NORMAN OK
1213 PM CDT SAT AUG 18 2001

THE STORM PREDICTION CENTER HAS ISSUED A
TORNADO WATCH FOR PORTIONS OF

CENTRAL ILLINOIS
WEST CENTRAL AND NORTHWEST INDIANA

EFFECTIVE THIS SATURDAY AFTERNOON AND EVENING FROM 1230 PM UNTIL
600 PM CDT.

TORNADOES...HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS
TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.

THE TORNADO WATCH AREA IS ALONG AND 90 STATUTE MILES EAST AND WEST
OF A LINE FROM 20 MILES SOUTH OF DECATUR ILLINOIS TO 55 MILES NORTH
OF LAFAYETTE INDIANA.

REMEMBER...A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR
TORNADOES AND 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.

DISCUSSION...STORMS ARE EXPECTED TO INCREASE IN COVERAGE/INTENSITY
ACROSS CENTRAL IL THE NEXT 1-2 HOURS...AND SPREAD EWD INTO INDIANA
IN ADVANCE OF A STRONG MID LEVEL TROUGH MOVING SEWD ACROSS ERN IA.
SBCAPE VALUES OF 2000-3000 J/KG WILL COMBINE WITH INCREASING DEEP
LAYER SHEAR TO SUPPORT A SUPERCELL THREAT.  ADDITIONALLY...MOIST
LOW LEVELS AND MODEST LOW-LEVEL SHEAR WILL SUPPORT THE THREAT OF A
FEW TORNADOES E OF THE DEVELOPING SURFACE LOW NEAR UIN.

AVIATION...TORNADOES AND 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 28025.

...THOMPSON