As snowlakes began to fall to the north of the city, the Illinois Tollway on Thursday sent out its full fleet of 183 snowplows to cover the 286 miles of interstate.
To help with snow removal efforts, the Tollway has cancelled all temporary lane closures from 5 p.m. Thursday through noon on Friday.
"It is possible that this storm could impact drivers this evening as well as tomorrow's morning rush hour, so we ask our customers to drive safely and allow enough time to arrive at their destinations," said Illinois Tollway Executive Director Kristi Lafleur.
In a tweet, NBC Chicago traffic reporter Matt Rodewald marveled at the size of the snowflakes.
By 5 p.m. Thursday, Chicago's airports had already been affected by the storm. Southwest Airlines cancelled all Thursday evening flights in and out of Midway as well as some scheduled for Friday morning.
Travelers are strongly advised to check ahead.
A Winter Weather Advisory begins at 6 p.m., with several inches of snow expected overnight. The city could see eight inches of snow by the end of the storm, while the western suburbs could get about four. Accumulation north of the city could reach about eight or nine inches.