WATCHES: Severe Thunderstorm Watch Number 803

WWUS20 KWNS 242313
SEL3
SPC WW 242313
ILZ000-INZ000-MIZ000-MOZ000-OHZ000-250700-

URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 803
NWS STORM PREDICTION CENTER NORMAN OK
605 PM CDT WED AUG 24 2011

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

WEST CENTRAL THROUGH MUCH OF EASTERN ILLINOIS
WESTERN AND NORTHERN INDIANA
FAR SOUTHERN LOWER MICHIGAN
EAST CENTRAL MISSOURI
NORTHWEST OHIO

EFFECTIVE THIS WEDNESDAY NIGHT AND THURSDAY MORNING FROM 605 PM
UNTIL 200 AM CDT.

HAIL TO 2 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 115
STATUTE MILES EAST AND WEST OF A LINE FROM 70 MILES EAST
NORTHEAST OF SOUTH BEND INDIANA TO 30 MILES SOUTHEAST OF ALTON
ILLINOIS. FOR A COMPLETE DEPICTION OF THE WATCH SEE THE
ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU3).

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 802...

DISCUSSION...TSTMS EXPECTED TO INCREASE IN COVERAGE / STRENGTH OVER
WW AREA OVER THE NEXT FEW HOURS AS LARGE SCALE ASCENT INCREASES
ALONG AND AHEAD OF COLD FRONT ASSOCIATED WITH AMPLIFYING SHORTWAVE
TROUGH NOW OVER WI. CINH WILL INCREASE FOR NEAR-SFC PARCELS WITH
SUNDOWN. BUT COMBINATION OF STRONG INSTABILITY ABOVE THE BOUNDARY
LAYER...MODEST LOW LVL CONVERGENCE / LARGELY LINEAR LOW LVL FORCING
ALONG/AHEAD OF FRONT...AND SEASONABLY STRONG WIND FIELD /ESPECIALLY
IN NRN HALF OF WW/ SUGGESTS POTENTIAL FOR A FEW SUPERCELLS/SUSTAINED
MULTICELL CLUSTERS WITH SVR WIND/HAIL. THESE MAY EVOLVE INTO ONE OR
TWO LARGER MCSS WITH EMBEDDED BOWING SEGMENTS LATER THIS EVE/EARLY
THU.

AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT
TO 2 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60
KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 550. MEAN STORM
MOTION VECTOR 31525.

...CORFIDI

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