The Chicago area is under its first Blizzard Warning since Super Bowl Sunday 2015, and is expected a transition to snow over all but the extreme southeast sections of the city by 9 p.m. or 10 pm, and in northwest Indiana and our far southern suburbs between 11 p.m. and 1 a.m.
Blizzard conditions will lock in at that point and snow will fall steadily until 6 a.m. to 8 am, and in northwest Indiana it may linger as wind-driven lake effect snow showers into mid- and late morning. Powerful storm dynamics may generate additional thundersnow, with reports of thundersnow over the past several hours in Amboy and Mendota in LaSalle County around 6 p.m. 2 inches of snow fell there in just 40 minutes during the thundersnow episode.
Snow is already stacking up in the north and west suburbs, with up to 7" already down in Rockford and up to 16" down in Iowa at Osceola. Powerful wind gusts have hit and topped 60 mph across a multi-state area in the Plains and western Midwest. And winds are building in the Chicago area, where gusts of 40 to 60 mph may sweep off Lake Michigan as the night proceeds, building waves of 16 feet or more, which will pound the shoreline producing some flooding.
Snowfalls of 8" to 14" are anticipated in the west and northwest suburbs; 6" to 13" in the city--heaviest west and north sections; and 2" to 6" in the south suburbs and northwest Indiana, whipped by winds which may produce near whiteout or whiteout conditions in the overnight hours.