(10:45PM - 12/27/21) A storm system is expected to move through the region on Tuesday. This storm system will bring a period of accumulating snow across Northern Illinois, Tuesday morning through Tuesday evening.
A storm system will move from the Plains on Tuesday morning, into the Northern Great Lakes by Tuesday night. This storm system will bring a period of accumulating snow across Northern Illinois, Tuesday morning through Tuesday evening, before precipitation changes to rain and/or ends.
With this update we slightly raised expected snowfall totals in the Chicago metro area and across Northwest Illinois, otherwise no significant changes were needed. At this time there continues to be some uncertainty and model disagreement regarding this event. Stay tuned for future updates.
Precipitation is expected to spread into Central Illinois early Tuesday morning, in the form of rain, though there could be a brief mix for some areas. As precipitation pushes northeastward into Northern Illinois Tuesday morning, it will work into colder air, allowing for a transition to snow. Snow will be likely across Northern Illinois for a several our period of time, from Tuesday morning through Tuesday evening. As milder air works northward and the back-edge of the precipitation shield moves in, snow will change over to a bit of rain/drizzle and end Tuesday evening.
Snowfall totals upwards of 1-3" is expected across much of Northern Illinois with this event, with 2-5" being possible across far Northwest Illinois. With temperatures hovering around freezing for this event, this will be a wet snow, which accumulates best of colder surfaces with some melting during the event.
Below is the snowfall forecast for this event.