Update 3:40AM CST…
The Winter Weather Advisory has been dropped early this Monday morning with most of the freezing drizzle/light snow moving off to the east and the causal low pressure weakening as it drifts overhead. Temperatures are hovering in the lower 30s, so most treated highways/streets are wet. Travelers and individuals out and about may still have to be alert for icy/slick spots on untreated side roads, streets, sidewalks, and parking lots.
As low pressure moves off to the east and dissipates this morning, the associated low cloud layer will probably persist – the day ahead will be overcast, but precipitation-free for the most part. Temperatures will likely not change much – topping-out in the middle to upper 30s at best.
A Winter Weather Advisory has been issued for the entire Chicago area (purple-shaded counties on the headlined map) until early Monday morning. The special statement issued earlier this evening has subsequently been upgraded to the area-wide Advisory.
With temperatures hovering in the middle 20s to lower 30s, patchy freezing drizzle mixed with snow will cause slick/dangerous conditions for travel as well as general outdoor activities across the entire Chicago area (northeast Illinois into northwest Indiana) overnight. Indications are that heaviest precipitation and subsequently the area most likely to experience dangerous glazing, will be the northernmost section along the Illinois/Wisconsin state line. Thus even though the drizzle and light snow may occur south of Interstate 80, the farther north you go, the worse the conditions could be.
Precipitation should gradually diminish and end from the west by sunrise or shortly thereafter.