

914 

WWUS20 KWNS 280251

SEL6

SPC WW 280251

INZ000-MIZ000-OHZ000-LEZ000-LHZ000-LMZ000-281000-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 746

NWS STORM PREDICTION CENTER NORMAN OK

1045 PM EDT SUN SEP 27 2009



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       NORTHERN INDIANA

       SOUTHERN AND CENTRAL MICHIGAN

       NORTHWEST OHIO

       LAKE ERIE

       LAKE HURON

       LAKE MICHIGAN



EFFECTIVE THIS SUNDAY NIGHT AND MONDAY MORNING FROM 1045 PM UNTIL

600 AM EDT.



HAIL TO 0.5 INCH IN DIAMETER...THUNDERSTORM WIND GUSTS TO 80

MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.



THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 95

STATUTE MILES EAST AND WEST OF A LINE FROM 35 MILES SOUTHWEST OF

FORT WAYNE INDIANA TO 35 MILES WEST NORTHWEST OF SAGINAW

MICHIGAN.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU6).



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 745...



DISCUSSION...TSTMS NOW FORMING ALONG STRENGTHENING COLD FRONT OVER

ERN WI/NRN IL EXPECTED TO FUSE INTO A NEARLY SOLID LINE AS UPR VORT

NOW NEAR MSP AMPLIFIES SEWD.  ALTHOUGH SFC-BASED INSTABILITY WILL

REMAIN LIMITED GIVEN TIME OF DAY AND UPSTREAM MOISTURE ENVIRONMENT

...STRENGTH OF DEEP WIND FIELD...INCREASING LARGE SCALE ASCENT...AND

FRONTAL UPLIFT TOGETHER EXPECTED TO SUPPORT A LINE OF STG TO SVR

CONVECTION/STORMS.  EMBEDDED SUPERCELLS/BOWING STRUCTURES COULD

YIELD DMGG WIND...MARGINALLY SVR HAIL...AND PERHAPS A TORNADO IN

LEFT EXIT REGION OF 100+ KT 500 MB JET STREAK.



AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT

TO 0.5 INCH. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 70

KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 350. MEAN STORM

MOTION VECTOR 26050.





...CORFIDI

