

913 

WWUS20 KWNS 230842

SEL3

SPC WW 230842

IAZ000-ILZ000-INZ000-WIZ000-LMZ000-231500-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 393

NWS STORM PREDICTION CENTER NORMAN OK

340 AM CDT WED JUN 23 2010



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       EAST CENTRAL IOWA

       NORTHERN ILLINOIS

       FAR NORTHWEST INDIANA

       EASTERN WISCONSIN

       LAKE MICHIGAN



EFFECTIVE THIS WEDNESDAY MORNING FROM 340 AM UNTIL 1000 AM CDT.



HAIL TO 1.5 INCHES 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 90

STATUTE MILES EAST AND WEST OF A LINE FROM 25 MILES NORTH

NORTHWEST OF GREEN BAY WISCONSIN TO 15 MILES WEST SOUTHWEST OF

MARSEILLES 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 387...WW 388...WW

389...WW 391...WW 392...



DISCUSSION...A FORWARD-PROPAGATING/BOW MCS APPEARS TO BE EVOLVING

ATTM OVER NERN IA.  SOME ADDITIONAL SWD DEVELOPMENT...PERHAPS TO THE

I-80 CORRIDOR...MAY OCCUR OVER THE NEXT FEW HOURS IN RESPONSE TO

ARRIVAL OF STRONGER ASCENT AND LOW-LVL WIND SHIFT ATTENDANT TO

NEB/SD SHORTWAVE TROUGH.  HI PW VALUES AND STRENGTHENING WIND FIELD

WITH CONTINUED EWD MOTION OF UPR IMPULSE SUGGEST GOOD CHANCE FOR

DMGG WIND AND POSSIBLY SVR HAIL WITH BOW.  OTHER SVR STORMS MAY

OCCUR IN ERN WI AS SLIGHTLY ELEVATED CONVECTION NOW ALONG AND N OF

W/E ALONG WARM FRONT GRADUALLY BECOMES MORE NEARLY SFC-BASED.  WHILE

A TORNADO OR TWO COULD NOT BE RULED OUT...DMGG WIND SHOULD BE THE

MAIN SVR THREAT.



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

TO 1.5 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 70

KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500. MEAN STORM

MOTION VECTOR 27040.





...CORFIDI

