Showers and thunderstorms are possible this afternoon and overnight. The highest chance for rain is between 8:00 p.m. and 8:00 a.m. overnight to Friday.
The weather environment is expected to be unstable tonight with a chance of cloud to ground lightning, large hail, high winds and an isolated tornado. The higher risk for tornados is in southern Iowa, northern Missouri, southeast Nebraska, and northeast Kansas.
Forecasters are also watching for the possibility of training of thunderstorms across northern Illinois, when continuous thunderstorms pass through the area and produce heavy rainfall. The training of thunderstorms largely depends on how slowly a frontal boundary — currently in Iowa, Minnesota and Wisconsin — moves southward across our area.
Forecast High Temperatures from North-to-South
Madison, Wisconsin …77°F
Waukesha, Wisconsin … 78°F
Kenosha, Wisconsin … 78°F
Lake Geneva, Wisconsin … 79°F
Arlington Heights, Illinois … 83°F
Joliet, Illinois … 86°F
Kankakee, Illinois … 87°F
Champaign, Illinois … 87°F
Today: A 30 percent chance of showers and thunderstorms, mainly after 1pm. Partly sunny, with a high near 83. Southwest wind around 15 mph, with gusts as high as 25 mph.
Tonight: Showers and thunderstorms. Low around 63. West southwest wind between 5 and 15 mph. Chance of precipitation is 80%. New rainfall amounts between a half and three quarters of an inch possible.
Friday: A 40 percent chance of showers and thunderstorms. Mostly cloudy, with a high near 76. Calm wind becoming northeast between 5 and 10 mph.
Hazardous Weather Outlook
HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
444 AM CDT THU MAY 3 2012
WINNEBAGO-BOONE-MCHENRY-LAKE ILLINOIS-OGLE-LEE-DE KALB-KANE-
444 AM CDT THU MAY 3 2012 /544 AM EDT THU MAY 3 2012/
THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTH CENTRAL ILLINOIS…
NORTHEAST ILLINOIS AND NORTHWEST INDIANA.
.DAY ONE…TODAY AND TONIGHT.
WEATHER HAZARDS EXPECTED:
SCATTERED THUNDERSTORMS…SOME MAY PRODUCE:
HAIL TO ONE INCH.
DAMAGING WIND GUSTS IN EXCESS OF 60 MPH.
HEAVY RAINFALL…WHICH COULD LEAD TO LOCALIZED FLOODING.
CLOUD TO GROUND LIGHTNING.
AREAS AFFECTED AND TIMING:
THUNDERSTORMS ARE EXPECTED TO DEVELOP DURING THE LATE MORNING
HOURS AHEAD OF A FRONTAL BOUNDARY ACROSS EASTERN IOWA. THUNDERSTORMS
ARE EXPECTED TO INCREASE IN COVERAGE AND SPREAD EAST INTO NORTHERN
ILLINOIS DURING THE EARLY TO MID AFTERNOON HOURS…AND EVENTUALLY INTO
NORTHWEST INDIANA LATE THIS AFTERNOON AND EARLY EVENING. THE POTENTIAL
FOR SEVERE THUNDERSTORMS WILL BE ACROSS ALL OF NORTHERN ILLINOIS
THIS AFTERNOON THROUGH TONIGHT.
A COMPLEX OF THUNDERSTORMS EARLY THIS MORNING OVER CENTRAL AND
WESTERN IOWA WILL CONTINUE TO WEAKEN TOWARDS DAYBREAK. DEBRIS
CLOUDS WILL SLIDE OVER NORTHERN ILLINOIS AND NORTHWEST INDIANA
LATE THIS MORNING. THE ATMOSPHERE SHOULD REMAIN CAPPED FOR MOST OF
THE MORNING AND POTENTIALLY INTO THE EARLY AFTERNOON HOURS. THEN
BY THIS AFTERNOON SURFACE INSTABILITY SHOULD BE ABLE TO OVERCOME
THE CAPPED ENVIRONMENT…WITH VERY UNSTABLE CONDITIONS DEVELOPING
OVER NORTHERN ILLINOIS AND NORTHWEST INDIANA.
ISOLATED THUNDERSTORMS OVER EASTERN IOWA SHOULD DEVELOP LATER THIS
MORNING…AND CONTINUE TO DEVELOP AND SPREAD EAST INTO NORTHERN
ILLINOIS BY THIS AFTERNOON…EVENTUALLY REACHING NORTHWEST INDIANA
LATE THIS AFTERNOON. THUNDERSTORMS WILL THEN CONTINUE THROUGH
TONIGHT AS A SLOW MOVING FRONTAL BOUNDARY APPROACHES FROM THE
NORTHWEST. SOME OF THE STORMS COULD BE SLOW MOVING LATER THIS
EVENING…AND RESULT IN ISOLATED HEAVY RAINFALL TOTALS. THIS COULD
POTENTIALLY LEAD TO LOCALIZED FLASH FLOODING.
THE PRIMARY CONCERN FROM SEVERE THUNDERSTORMS WILL BE LARGE HAIL
UP TO ONE INCH…AND DAMAGING WINDS IN EXCESS OF 60 MPH. IN
ADDITION…THE POTENTIAL WILL EXIST FOR A FEW OF THE STRONGEST
THUNDERSTORMS TO HAVE ROTATING UPDRAFTS. THIS COULD RESULT IN AN
ISOLATED TORNADO ACROSS THE OUTLOOK AREA.
.DAYS TWO THROUGH SEVEN…FRIDAY THROUGH WEDNESDAY.
THERE WILL BE PERIODIC CHANCES FOR THUNDERSTORMS FOR THE ENTIRE
OUTLOOK AREA THROUGH THE REMAINDER OF THE WEEK. SOME POTENTIAL
WILL EXIST FOR SEVERE THUNDERSTORMS FRIDAY…WITH THE PRIMARY
THREATS BEING LARGE HAIL AND DAMAGING WIND.
.SPOTTER INFORMATION STATEMENT…
SPOTTERS MAY BE NEEDED THIS AFTERNOON THROUGH TONIGHT.
COMPLETE FORECAST INFORMATION IS AVAILABLE ON THE NWS CHICAGO
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