CHICAGO — About 350 flights at Midway and O'Hare airports were canceled in anticipation of winter weather, according to the Chicago Aviation Deparment, and Southwest Airlines has canceled all flights after 4:30 p.m. Thursday.
More than 200 flights have been canceled at O'Hare, and about 150 Midway flights have been canceled.
At O'Hare, the city reported delays between 30 and 90 minutes. Travelers hoping to catch their flights should call their airlines for specific information and show up early at the airport, the department said.
The National Weather Service warned of strong thunderstorms, snow accumulation, powerful winds and blizzard conditions in the Chicago area. The rain will change to snow during the afternoon and evening, according to a winter storm warning that goes into effect from 3 p.m. and lasts until 3 a.m. Friday.
Forecasters are predicting 2 to 4 inches of snow, including thundersnow and blowing snow, according to Andrew Krein, a meteorologist with the National Weather Service in Romeoville.
"The snowfall rates will be much higher," Krein said. "With thundersnow, you can see snowfall rates of 2, 3, 4 inches per hour."
"It's typically associated with very strong systems," he added.
Most of the snow accumulation is expected north and northwest of the city. The biggest problem will not be the snowfall, but the high winds mixing with precipitation and causing low visibility, Fenlon said.
Winds could reach 50 to 60 mph and result in downed power lines and tree limbs. Travelers were urged to take caution and avoid driving.
Public transportation ran as usual Thursday morning, and weather-related delays were not expected, Metra spokesman Tom Miller said.
ComEd made special preparations in anticipation of power outages, including mobilizing contractor and assistance crews, according to a statement. The company is asking customers to call (800) 334-7661 or visit its website to report outages.
Treacherous winds are expected to continue into Friday, along with more snow.
If the city measures at least one-tenth of an inch of snow at O'Hare, it would be the first measurable snowfall of the season.
The city has gone 290 consecutive days without snow — the longest period on record.