Updated 02/05/14 – 11:20 a.m.

CHICAGO (CBS) — Heavy, blowing snow was making Chicago area roads very treacherous early Wednesday, and airlines were cancelling hundreds of flights at O’Hare and Midway airports due to the winter storm.

The official total for Chicago as of late Wednesday morning was the 5 inches that fell at O’Hare International Airport, but Midway International Airport got a bit more, with 5.9 inches of snow. Some suburbs reported more than 7 inches of snow, and parts of northwest Indiana got more than 8 inches.

A winter weather advisory for most of the Chicago area remains in effect until 2 p.m.

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Chicago’s Department of Streets and Sanitation has deployed more than 200 plows on city streets. The trucks were battling traffic as they tried to clear the city’s main streets for the morning commute. Crews won’t tackle the side streets until they have a handle on the major roads.

Travel was slow on all Chicago area interstates, as blowing snow reduced visibility and kept roads slick.

The snowfall was an even bigger problem in some suburbs where crews already were running low on road salt before the winter storm hit Tuesday afternoon.

For example, in west suburban Berwyn, even though Cermak Road has been plowed several times since the storm started, the street was still covered in heavily packed snow, because crews could not put down enough salt to melt what plows couldn’t scrape off the road.

Snow was expected to continue falling through the morning commute, and after that blowing and drifting snow were likely to continue making travel problematic.

At O’Hare airlines cancelled more than 370 flights early Wednesday, after cancelling more than 380 flights on Tuesday. At Midway International Airport, more than 45 flights were cancelled early Wednesday, after another 40 were cancelled on Tuesday. Many other flights at both airports were being delayed by the weather, so passengers should check with their airline before heading to the airport.

Meantime, Metra was advising commuters to expect some delays and service disruptions on Wednesday. Several lines were reporting delays early Wednesday, in some cases up to 40 minutes, because of problems with switches and other equipment.

Metra officials said they’re trying hard to keep the trains moving, and they appreciate people’s patience.

“Metra will continue to utilize all possible measures available to combat extraordinary weather conditions. We regret any unanticipated weather-related delays,” the agency said in a weather alert on its website.

For other commuters, the CTA was not reporting any service issues or major delays on its trains as of early Wednesday, though some buses were moving slower than normal due to slick streets.

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