WATCHES: Severe Thunderstorm Watch Number 264

WWUS20 KWNS 072004
SEL4
SPC WW 072004
ILZ000-INZ000-080300-

URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 264
NWS STORM PREDICTION CENTER NORMAN OK
300 PM CDT SAT MAY 7 2011

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

EAST CENTRAL ILLINOIS
WESTERN AND CENTRAL INDIANA

EFFECTIVE THIS SATURDAY AFTERNOON AND EVENING FROM 300 PM UNTIL
1000 PM CDT.

HAIL TO 2.5 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 70
STATUTE MILES NORTH AND SOUTH OF A LINE FROM 30 MILES WEST
NORTHWEST OF BLOOMINGTON ILLINOIS TO 35 MILES EAST NORTHEAST OF
INDIANAPOLIS INDIANA. FOR A COMPLETE DEPICTION OF THE WATCH SEE
THE ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU4).

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...EXPECT STORM DEVELOPMENT TO CONTINUE TO INCREASE OVER
THE NEXT FEW HOURS AS UPPER SHORT WAVE TROUGH AND ASSOCIATED SURFACE
LOW TRACK ESEWD ACROSS THE WATCH AREA. STORMS WILL BE DEVELOPING
WITHIN MODERATELY UNSTABLE AIRMASS WHERE SBCAPE WILL BE AROUND 1000
J PER KG. 50-60KT MID LEVEL WIND MAX ATOP LOW LEVEL SLY FLOW SHOULD
CONTRIBUTE TO EFFECTIVE SHEAR SUPPORTIVE OF PERSISTENT ROTATING
UPDRAFTS CAPABLE OF PRODUCING LARGE HAIL. GENERALLY WEAK LOW LEVEL
SHEAR SHOULD OFFSET TORNADO THREAT BUT AN ISOLATED/LOW PROBABILITY
POTENTIAL FOR A WEAK/BRIEF TORNADO MAY EVOLVE NEAR THE WEAK SURFACE
LOW...AND ALONG OUTFLOW-REINFORCED WARM FRONT ACROSS NRN PORTIONS OF
THE WATCH.

AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT
TO 2.5 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60
KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 400. MEAN STORM
MOTION VECTOR 30025.

...CARBIN

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