As much as a couple inches of light fluffy snow could fall overnight in Lake, McHenry, and northern Cook Counties with lesser amounts across Kane and Du Page Counties. The center of low pressure will continue to move east through northern Lower Michigan tonight. A trough of low pressure extends back southwest out of the low into the northeast corner of Illinois.
The trough of low pressure will drift slowly east with the low center coinciding with a band of moisture aloft that will act in concert with the trough causing snowfall to continue at a steady rate into the early morning hours. Snow will accordingly slowly accumulate with greatest amounts along and just inland of the Lake and northern Cook County shoreline. Lesser amounts will accumulate back to the west.
West winds will gradually shift to the northwest gusting over 30 miles per hour – leading to some drifting and blowing snow in these counties tonight. Snow should be well to the east of Chicago by sunrise Wednesday morning with winds also somewhat lighter.