Dangerous travel/outdoor conditions are expected to develop across the Chicago area later this afternoon and continue overnight. A Winter Weather Advisory (purple-shaded counties on the headlined map) is in effect for the entire Chicago area Friday afternoon through Friday night ending early Saturday morning.
Accumulating snow is expected to begin in westernmost sections mid-afternoon Friday, spreading across the entire area into northwest Indiana by early evening. Snow will change over to freezing rain and sleet with a wintry mix persisting much of the night turning over to rain in many areas before diminishing/ending Saturday morning. Snow accumulations will range from 1 to 3-inches across counties along and south of Interstate-80 into NW Indiana to as much as 2 to 5-inches across the remainder of the area, including the City of Chicago (greatest amounts in northernmost counties).
Low pressure will move northeast out of the plains, passing well north of our area Saturday forenoon. In its wake, strong west-northwest winds gusting over 40 mph will pull colder air and snow showers across northern Illinois and NW Indiana later Saturday morning and the remainder of the day. The Winter Weather Advisory for possible additional accumulating snow/blowing snow and hazardous travel will continue in northwestern counties Saturday. Temperatures will be falling Saturday afternoon with single-digit readings and sub-zero wind chills area-wide Saturday night.
Heavier snow/blowing snow is likely farther north of the low pressure center across Minnesota and Wisconsin into Michigan.