WATCHES: Tornado Watch Number 745

WWUS20 KWNS 280130
SEL5
SPC WW 280130
ILZ000-INZ000-WIZ000-LMZ000-280700-

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 745
NWS STORM PREDICTION CENTER NORMAN OK
825 PM CDT SUN SEP 27 2009

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

NORTHERN AND CENTRAL ILLINOIS
NORTHWEST INDIANA
SOUTHEAST WISCONSIN
LAKE MICHIGAN

EFFECTIVE THIS SUNDAY NIGHT AND MONDAY MORNING FROM 825 PM UNTIL
200 AM CDT.

TORNADOES...HAIL TO 1 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 60 STATUTE
MILES EAST AND WEST OF A LINE FROM 30 MILES NORTH OF MILWAUKEE
WISCONSIN TO 35 MILES SOUTH OF DECATUR ILLINOIS. FOR A COMPLETE
DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE UPDATE
(WOUS64 KWNS WOU5).

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...TSTMS EXPECTED TO INCREASE ALONG COLD FRONT AND ALONG
PRE-FRONTAL CONFLUENCE AXIS OVER SRN WI/IL...AHEAD OF STRONG/
AMPLIFYING SHORTWAVE TROUGH NOW OVER SE MN. ALTHOUGH THE
PRE-FRONTAL ACTIVITY LIKELY WILL REMAIN SLIGHTLY ELEVATED...
AND...WITH TIME...LINEAR FORCING FOR ASCENT WILL INCREASE ALONG COLD
FRONT...FOR THE NEXT FEW HOURS A QUASI-DISCRETE STORM MODE IS
EXPECTED TO PREVAIL. GIVEN MAGNITUDE OF DEEP SHEAR /AOA 60
KTS/...SUPERCELL STRUCTURES LIKELY WILL BE ASSUMED BY ANY SUSTAINED
UPDRAFTS. INFLUX OF SOMEWHAT MORE SUBSTANTIAL MOISTURE NOW NEAR STL
INTO CNTRL/NRN IL STORMS LATER TONIGHT FURTHER SUGGESTS POSSIBLE
TORNADOES GIVEN FACT THAT FLOW IMMEDIATELY AHEAD OF FRONT SHOULD
MAINTAIN A SIZABLE SLY COMPONENT BENEATH 50+ KT WLY 700 MB FLOW.

AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 1 INCH. EXTREME TURBULENCE AND SURFACE WIND
GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 350.
MEAN STORM MOTION VECTOR 26050.

...CORFIDI

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