Weather will be a major player across the Midwest and Chicago area during the next 24 hours. Low pressure is expected to intensify as it tracks east-northeast out of Kansas, passing just south of Chicago overnight, moving off to the east Monday. Heavy rains will develop along and north of the associated warm-frontal boundary (see synoptic map below). There will be flash-flood/flooding potential with 1 to 3-inch-plus 24-hour rainfall totals possible, especially along and south of Interstate-80.
In addition strengthening easterly winds will gust over 40 mph building waves and causing lakeshore flooding along the Illinois/Indiana Lake Michigan shoreline. Severe storms are likely to develop In the warm sector of the storm system and along the warm front, mainly across southern/central Illinois/Indiana later this afternoon, possibly reaching as far north as our far southern counties.
Note the time-lines displays below on all these events produced by the Chicago National Weather Service Forecast Office.