

000 

WWUS20 KWNS 180658

SEL9

SPC WW 180658

ILZ000-181400-



URGENT - IMMEDIATE BROADCAST REQUESTED

TORNADO WATCH NUMBER 719

NWS STORM PREDICTION CENTER NORMAN OK

155 AM CDT THU OCT 18 2007



THE NWS STORM PREDICTION CENTER HAS ISSUED A

TORNADO WATCH FOR PORTIONS OF



       CENTRAL ILLINOIS



EFFECTIVE THIS THURSDAY MORNING FROM 155 AM UNTIL 900 AM CDT.



TORNADOES...HAIL TO 0.5 INCH IN DIAMETER...THUNDERSTORM WIND

GUSTS TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE

AREAS.



THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 55 STATUTE

MILES EAST AND WEST OF A LINE FROM 35 MILES NORTH NORTHWEST OF

PEORIA ILLINOIS TO 30 MILES EAST OF SALEM ILLINOIS.  FOR A

COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE

UPDATE (WOUS64 KWNS WOU9).



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.



OTHER WATCH INFORMATION...CONTINUE...WW 715...WW 716...WW

717...WW 718...



DISCUSSION...BAND OF LOW-TOPPED STORMS OVER WRN IL EXPECTED TO

CONTINUE E INTO CNTRL IL LATER THIS MORNING AS EMBEDDED STORMS MOVE

MORE RAPIDLY NNE ALONG IT.  CONVECTIVE SYSTEM IS IN ENVIRONMENT OF

WEAK SFC-BASED INSTABILITY BUT VERY STRONG LOW AND DEEP LYR

SHEAR...AND IS BEING FORCED...IN PART...BY ASCENT ASSOCIATED WITH

ERN KS UPR TROUGH.  AS KS TROUGH ASSUMES MORE OF A NEGATIVE TILT AND

CONTINUES NNE OVER THE NEXT FEW HOURS...FORCING MAY BE SUFFICIENT TO

MAINTAIN SQLN AND ASSOCIATED SVR WIND/ISOLATED TORNADO THREAT.



AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL

SURFACE AND ALOFT TO 0.5 INCH. EXTREME TURBULENCE AND SURFACE

WIND GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO

400. MEAN STORM MOTION VECTOR 21040.





...CORFIDI

