

039 

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

