As Arctic-source high pressure rests over most of the U.S. east of the Rockies, an upper-air disturbance originating in the central Rockies will quickly track east, leaving a band of 2-4 inches of snow from Nebraska and Missouri, then along and south of Interstate 70 all the way to the Appalachians.
Most of the snow will hit central and southern Illinois before noon Thursday, just brushing the Chicago area. The farther south, the better the chance of snow-covered, slick highways.
A persistent, strong northwest flow aloft will keep reinforcing the Arctic cold over the Midwest and Great Lakes, resulting in Chicago-area temperatures Thursday through Sunday averaging 11.5 degrees below normal, with daytime highs in the teens to low 20s. South winds will fuel a warmup the first part of next week along with a chance of snow Monday and rain Tuesday.
