Schools closing because of the weather conditions is one thing, but hundreds of flights being cancelled, combined with power outages across the region is an added layer of difficulty.

With a mix of snow, sleet and freezing rain this morning, the National Weather Service cautioned that “significant icing” could accumulate, as much as half an inch throughout our area and Chicagoland.

Because of ice that fell overnight on overhead power lines, train service on the South Shore Line and Metra Electric District was temporarily suspended Tuesday, according to a service alert.

In the Chicago area, several of the main arteries for the morning commute, including the Kennedy, Edens and Eisenhower expressways, as well as many roads in Cook, Lake and McHenry counties were either covered in ice and snow or partly covered in ice and snow, according to the Illinois Department of Transportation’s website.

Chicago Tribune:

In addition to transportation problems, about 11,000 Commonwealth Edison customers were without power throughout much of northern Illinois as of 7 a.m., according to John Schoen, a spokesman for the utility. He said power already had been restored to 34,000 customers who had lost power earlier in the day, between midnight and 7 a.m.

“With a storm like this, it’s not just iced lines,” Schoen said. “It’s tree branches that get coated in ice and then a branch that maybe weighed 10 pounds suddenly weighs 20 pounds and it snaps off, hitting a power line.”

Strong westerly winds were expected to develop, increasing the threat of power outages later Tuesday into the night.

The weather was also forcing cancellations at O’Hare and Midway airports. By 7 a.m. there had been 263 cancelled flights at O’Hare over the previous 24 hours, 127 of them departures. At Midway, there had been 82 cancelled flights, 41 of them departures.

The National Weather Service Tuesday released ice measurements at 6 a.m. The Aurora Airport, west of the city, recorded half an inch of ice. Midway had 0.46 inches; O’Hare 0.44 inches; and the Rockford Airport recorded 0.34 inches of ice.