White Christmas coming- Accumulating snow to spread across the Chicago area Sunday – Winter Weather Advisory for most of the area- Winter storm warnings for northwest Indiana
A Winter Weather Advisory is in effect for all but the far north portions of the Chicago area Sunday (purple-shaded area on the highlighted map above). Winter storm warnings have been issued for northwest Indiana.
An accumulating snow will spread from west to east across the Chicago area Sunday, beginning in western portions before sunrise and ending from the west later Sunday afternoon. Most areas should see accumulations on the order of 2 to 4-inches but with lesser accumulations of 1 to 3-inches farther north. Total snowfall could top 6 inches in portions of northwest Indiana where lake-effect will enhance snow totals
Eastward-moving low pressure will pass to our south Sunday, but an associated upper-air disturbance will track farther north over our area triggering an accumulating snow that will spread across central and northern Illinois beginning in western portions not long after midnight tonight, across the Chicago area by Sunday forenoon – then ending from the west later in the day. Northerly winds on the back-side of the departing low pressure could cause additional lake-enhanced snowfall in southernmost Cook County and far eastern Will County in Illinois, but mainly in northwest Indiana counties later Sunday afternoon/evening.