The week ahead starts off with a cold, dry arctic air mass still holding fast over the western Great Lakes and Midwest. However, jet stream flow aloft will shift from north to west midweek, allowing maritime cool air from the West Coast to finally penetrate into the central Plains. The warm-up should begin Thursday and peak Friday with 40°-plus high temperatures forecast for the first time this month. There have been only two Decembers in 135 years of record that did not have at least one 40° day—1983 and the snowy December of 2000—and two others, 1903 and 1919, only had a single 40° day.
The Northeast Illinois snow cover ranges from around 3 inches south to 6 inches north along the Wisconsin-Illinois border. As winds pick up Wednesday, warm air moves in Thursday and rain spreads over the area later Friday into Saturday. The snow pack will slowly diminish with a good chance of bare spots by Christmas Day.
WGN-TV Chief Meteorologist Tom Skilling and the WGN Weather Center staff provide daily coverage of weather in the Chicago area.
