A powerful ice storm sweeping across the Midwest led to treacherous travel in Illinois and the Chicago area, with officials reporting slick roads across the region Wednesday night into Thursday morning.

Weather watchers are forecasting a cold, gray week mostly in the 20s with two icy storms — part of a larger system sweeping across the Midwest and Northeast — that will likely create treacherous driving conditions in metro Detroit. But hopefully, forecasters added, they won’t be severe enough to take down powerlines.