Record cold on Saturday, and near-freezing temperatures across portions of the Chicago area Sunday morning, were the product of a deep, stationary storm system north of Lake Superior.
Known to meteorologists as a “cut-off” low, typical west-to-east movement of the system remains stalled. Cold air pooled around this low is forecast to erode by midweek, allowing the circulation to eventually shift to eastern Canada. As jet stream flow becomes more westerly, milder air will overspread the region.
Through the first five days of October, high temperatures at O’Hare have averaged 5.8 degrees below normal. Average daytime readings in the low 60s are forecast through Sunday, still about 5 degrees below normal, but without the November-like chill of this past weekend.
