Updated 03/25/13 – 10:14 a.m.

CHICAGO (CBS) — A winter storm that buried much of central Illinois in heavy snow largely missed the Chicago area Sunday and early Monday. The storm prompted many schools and universities downstate to cancel classes, and police advised people not to drive in that part of the state unless it’s an emergency.

According to the National Weather Service, the winter storm was over by early Monday. It left only a dusting of snow in the Chicago area, though lake effect showers and flurries were possible for the rest of the day on Monday. Downstate was a different story, however. Most of the central part of the state was slammed with heavy snow, with up to 18 inches in some places.

The Bloomington-Normal area saw up to 9.5 inches of snow. Urbana-Champaign saw nearly 11 inches. Decatur got about a foot of snow. Springfield got more than 18 inches in some spots by the time the storm ended.

The Chicago area saw only about an inch or two of snow, with most of the city getting only a dusting. O’Hare Airport reported 0.1 inches of snow early Monday; Midway Airport saw 0.6 inches.

At the University of Illinois’ Urbana-Champaign and Springfield campuses, classes were cancelled Monday due to the snow, but the campuses remained open, and staff were told they should decide for themselves if they can make it to work. Illinois State University in Normal was closed on Monday.

Illinois State Police were advising motorists to stay off I-57 and other roads south of Kankakee, except in emergencies, due to the heavy snow.

The snow is so bad downstate, state police are getting calls every 3 to 5 minutes about cars that are stranded.

“It is not getting any better,” said Illinois State Police Trooper Tracy Lillard. “We are still continuing, every 3 to 5 minutes, with another car in the ditch or stuck on a ramp or on an overpass.”

She says the roads are snow-plowed, but underneath there’s a 3-inch layer of snow and ice.

“The snow crew is out there trying to remove as much snow as possible, but it is just drifting and blowing very bad – since it’s wide open plains down here,” said Lillard.

Trooper Lillard says the main problem for drivers is, they’re just trying to drive too fast

Illinois State Police said, from 2 p.m. Sunday to 9 a.m. Monday, there were approximately 400 incidents on I-57 south of Kankakee, due to the weather – including crashes, stranded vehicles, and cars in ditches.

The worst conditions were along the corridor from Springfield to Urbana-Champaign on I-72, and from Paxton to Effingham on I-57.

Parts of I-55 and I-70 were also reported to be covered in ice or snow in central Illinois.

Many state and county roads in that part of the state were completely impassable, according to state police. Conditions on I-57 were bad “across the board,” with snow drifts in every direction.

As of 9:30 a.m., state police were not removing cars stuck in ditches, only assisting stranded motorists, some of whom were stranded 6 to 8 hours. State troopers were picking up motorists along the highway and taking them to the nearest gas stations and motels

State police requested emergency travel only on roads in that part of the state. Anyone who does drive should make sure they have a full tank of gas, a cell phone, and a cell phone charger, police said.

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