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URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 892

NWS STORM PREDICTION CENTER NORMAN OK

705 PM CDT MON SEP 8 2008



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       CENTRAL AND SOUTHERN ILLINOIS

       WESTERN AND CENTRAL INDIANA

       EAST CENTRAL MISSOURI



EFFECTIVE THIS MONDAY NIGHT AND TUESDAY MORNING FROM 705 PM UNTIL

200 AM 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 90

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

INDIANAPOLIS INDIANA TO 20 MILES EAST SOUTHEAST OF FARMINGTON

MISSOURI.  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...TSTMS NOW FORMING ALONG AND JUST N OF NE/SE COLD FRONT

THROUGH THE STL AREA EXPECTED TO CONTINUE GENERALLY EWD THROUGH LATE

EVE.  AREA VWP DATA SHOW 45-50 KT 700 MB WLY FLOW...BENEATH MODEL

FCST 90-100 KT WLY WINDS AT 250 MB.  COUPLED WITH MODERATE...NEARLY

SFC-BASED INSTABILITY AHEAD OF BOUNDARY...AND GLANCING INFLUENCE OF

PASSING NRN STREAM TROUGH...SETUP MAY SUPPORT A FEW SUSTAINED

STORMS/SUPERCELLS WITH SVR HAIL/WIND.  ABSENCE OF STRONG SFC WAVE

DEVELOPMENT EXPECTED TO KEEP SFC FLOW WEAK.  THIS SHOULD DIMINISH

RISK FOR TORNADOES.  HOWEVER...A TORNADO OR TWO CANNOT BE RULED OUT

GIVEN LENGTH OF LOW-LVL HODOGRAPHS AND SMALL TEMPERATURE-DEWPOINT

SPREADS.



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 450. MEAN STORM

MOTION VECTOR 27035.





...CORFIDI

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