A winter storm watch was issued Tuesday, and remains in effect until midnight Friday.
"Our latest MicroCast computer guidance strongly favors a scenario in which rain begins tomorrow night, then overspreads the area Thursday. Morning rush should be simply wet," ABC7 Meteorologist Mike Caplan said.
As colder air moves in Thursday morning and strengthens the storm, the rain will change to snow from west to east. Snow could fall all day Thursday- from sunrise to the evening. Overall accumulation will be limited, but heavy winds of up to 50 mph could create near-blizzard conditions.
"Travel during evening rush on Thursday will be horrendous," Caplan said.
Anyone with travel plans should be prepared for possible dangerous winter conditions as well as significantly increased travel times.
On Tuesday, Chicago broke a record for the longest stretch without measurable snow- 289 days. The last record was 281 days.