A Winter Weather Advisory is in effect for all but the northern most portions of the Chicago area Sunday (Purple-shaded area on the highlighted map above). Winter Storm Warnings (pink-shaded areas on map above) are in effect for portions of northwest Indiana. Roads/highways will be snow-covered and slick.
An accumulating snow will spread from west to east across the Chicago area Sunday, gradually ending from the west later this Sunday afternoon/early evening. Most of the area could see accumulations of 3 to 5-inches with lesser accumulations of 1 to 3-inches far north in counties adjacent to the Illinois-Wisconsin state line. Snowfall may total over 6-inches in portions of northwest Indiana where lake-enhanced snowfall could combine with system snow .
Eastward-moving low pressure will pass well to our south and east Sunday, but an associated upper-air disturbance will track farther north over our area triggering the accumulating snow across the Chicago area. Northerly winds on the back-side of the departing low pressure could cause additional lake-enhanced snowfall in Will and Kankakee Counties in Illinois, but mainly in northwest Indiana counties later Sunday afternoon/evening.
Updates at Chicago Weather Center