

762 

WWUS20 KWNS 311933

SEL8

SPC WW 311933

ILZ000-INZ000-MIZ000-OHZ000-LEZ000-LHZ000-LMZ000-010400-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 408

NWS STORM PREDICTION CENTER NORMAN OK

335 PM EDT TUE MAY 31 2011



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       CENTRAL AND NORTHEAST ILLINOIS

       NORTHERN INDIANA

       CENTRAL AND SOUTHERN LOWER MICHIGAN

       NORTHWEST OHIO

       LAKE ERIE

       LAKE HURON

       LAKE MICHIGAN



EFFECTIVE THIS TUESDAY AFTERNOON FROM 335 PM UNTIL MIDNIGHT 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 110

STATUTE MILES EAST AND WEST OF A LINE FROM 45 MILES NORTH

NORTHWEST OF SAGINAW MICHIGAN TO 35 MILES SOUTHEAST OF CHAMPAIGN

ILLINOIS.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU8).



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 407...



DISCUSSION...SCATTERED THUNDERSTORMS ARE BEGINNING TO DEVELOP ALONG

AND AHEAD OF A COLD FRONT OVER IL.  THESE STORMS ARE EXPECTED TO

INCREASE IN COVERAGE AND TRACK RAPIDLY NORTHEASTWARD ACROSS THE

WATCH AREA THIS AFTERNOON AND EVENING.  STEEP LOW LEVEL LAPSE RATES

AND STRONG WINDS ALOFT WILL PROMOTE A RISK OF DAMAGING WINDS...WHILE

A VERY UNSTABLE AIR MASS SUGGESTS A RISK OF LARGE HAIL.



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 500. MEAN STORM

MOTION VECTOR 24040.





...HART

