WATCHES: Severe Thunderstorm Watch Number 457

WWUS20 KWNS 101805
SEL7
SPC WW 101805
ILZ000-INZ000-KYZ000-OHZ000-110100-

URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 457
NWS STORM PREDICTION CENTER NORMAN OK
205 PM EDT FRI JUN 10 2011

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

CENTRAL ILLINOIS
CENTRAL AND NORTHERN INDIANA
EXTREME NORTHERN KENTUCKY
WESTERN OHIO

EFFECTIVE THIS FRIDAY AFTERNOON AND EVENING FROM 205 PM UNTIL 900
PM EDT.

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 65
STATUTE MILES NORTH AND SOUTH OF A LINE FROM 50 MILES SOUTHWEST
OF DECATUR ILLINOIS TO 20 MILES NORTH NORTHEAST OF DAYTON OHIO.
FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH
OUTLINE UPDATE (WOUS64 KWNS WOU7).

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...THUNDERSTORM DEVELOPMENT IS EXPECTED IN THE NEXT 1-2
HOURS ALONG A CONFLUENCE BOUNDARY FROM CENTRAL IL INTO W CENTRAL
INDIANA...AND ALONG A RETREATING OUTFLOW BOUNDARY FROM SW OH INTO
CENTRAL INDIANA. AN ADDITIONAL INFLUENCE ON STORM FORMATION MAY BE
THE EWD PROGRESS OF A REMNANT MCV NEAR THE STL AREA. STRONG
INSTABILITY HAS DEVELOPED ALONG AND S OF THESE BOUNDARIES /MLCAPE OF
2500 J PER KG/...AND THIS AREA IS WITHIN THE SRN FRINGE OF THE
MODERATE WLY MIDLEVEL FLOW. ORGANIZED CLUSTERS WILL BE CAPABLE OF
PRODUCING DAMAGING WINDS AND LARGE HAIL THROUGH THE AFTERNOON. AN
ISOLATED TORNADO CANNOT BE RULED OUT ALONG THE RETREATING OUTFLOW
BOUNDARY IN CENTRAL/NE INDIANA WHERE LOW-LEVEL AND DEEP-LAYER SHEAR
WILL BE SOMEWHAT STRONGER.

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 27030.

...THOMPSON

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