Update, 9:59 a.m. Jan. 27:
A freezing rain advisory is now in effect for all of Northern Illinois.
The advisory, in effect from 11 a.m. until 7 p.m. today, replaces the winter storm watch that had previously been issued by the National Weather Service in Chicago.
The freezing rain is expected to start midday, with ice accumulations up to a couple tenths of an inch expected.
"Pavement and soil temperatures are below freezing, so any liquid precipitation will likely freeze on contact and result in icy and dangerous travel conditions on untreated roadways," National Weather Service officials said in their advisory statement. "Walkways could also turn to sheets of ice, making walking difficult and potentially dangerous."