WATCHES: Severe Thunderstorm Watch Number 892

WWUS20 KWNS 090007
SEL2
SPC WW 090007
ILZ000-INZ000-MOZ000-090700-

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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