

071 

WWUS20 KWNS 180047

SEL9

SPC WW 180047

ILZ000-INZ000-KYZ000-180700-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 669

NWS STORM PREDICTION CENTER NORMAN OK

745 PM CDT WED OCT 17 2012



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       SOUTHEAST ILLINOIS

       SOUTHWEST INDIANA

       WESTERN KENTUCKY



EFFECTIVE THIS WEDNESDAY NIGHT AND THURSDAY MORNING FROM 745 PM

UNTIL 200 AM CDT.



HAIL TO 0.5 INCH 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 55

STATUTE MILES EAST AND WEST OF A LINE FROM 40 MILES NORTH

NORTHWEST OF EVANSVILLE INDIANA TO 55 MILES EAST SOUTHEAST OF

PADUCAH KENTUCKY.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU9).



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 666...WW 667...WW 668...



DISCUSSION...PRE-FRONTAL SQLN IN SW IL/WRN KY EXPECTED TO CONTINUE

RAPIDLY ENEWD...SUPPORTED BOTH BY INCREASING DCVA WITH AMPLIFYING

TROUGH NOW ENTERING NW AR...AND BY TIGHTENING OF LOW-LVL CONFLUENCE

FIELD AS ASSOCIATED COLD FRONT OVERTAKES SQLN. THESE FACTORS APPEAR

TO BE EVIDENCED BY INCREASINGLY WELL-DEFINED PRESSURE RISE-FALL

COUPLET IN PLACE OVER ERN OK/NW AR AND SRN IL RESPECTIVELY. GIVEN

EXISTING SQLN AND 45+ KT SLY LLJ AHEAD OF IT...IT SEEMS PROBABLE

THAT SOME RISK OF DMGG WIND AND PERHAPS A BRIEF TORNADO COULD EXTEND

NEWD INTO PARTS OF IND...DESPITE INCREASINGLY DRY LOW-LVL

ENVIRONMENT WITH EWD EXTENT.



AVIATION...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 24045.





...CORFIDI

