Wet snow, predicted to sweep north suburban areas overnight, is to wind down Saturday morning while chilly rains ease elsewhere. A second weather system may re-ignite chilly rains and some wet north suburban snow Sunday afternoon and evening before winds shift northwest and the season’s strongest punch of frigid arctic air to date dives into the area Sunday night for a stay predicted to take it into Midweek before moderating.
Big snows slated over Upper Midwest
The heaviest weekend snows are predicted to Chicago’s north. As much as a foot of snow may bury Minnesota’s Arrowhead region from Duluth north and a half foot or more is possible over some other sections of central Minnesota and central and northern Wisconsin extending into Michigan's Upper Peninsula.
A dusting to as much as an inch or two or wet snow is possible from the two systems over Chicago's far northwest suburbs. The ground is warm so the accumulating snow isn't likely to last long and will tend to collect on grassy surfaces.
Winter storm watches and weather advisories were hoisted Friday across 11 states north and west of Chicago.
Weekend systems to expand snowpack, increasing Chicago’s vulnerability to cold air
A highly reflective snowpack slows warming by sending much of the sun’s energy back into space before it can heat the layer of air closest to the ground. In that way, a cover of snow facilitates the movement of cold air into the area. The expanding snowpack over the northern U.S. is to allow the chill to tighten its grip here.
Changing weather pattern to bring unseasonable early-month warmth to an end; December’s opening 7 days rank 6th warmest on record
Up to this point, December 2012’s been a mild one in Chicago. The month’s average temperature has been 45.5-degrees, 12.9-degrees above the long-term average reached and the mildest open to a December here in 11 years.