Hundreds of flights were canceled in the Chicago area as an arctic front brought persistent snow early Saturday, forecasters said. The winter weather advisory for Cook and Will counties expired at 9 p.m. Friday, but snow continued to fall overnight, NBC-TV, Chicago, reported. Temperatures dropped below 20 degrees Fahrenheit behind the front, turning wet roads into frozen hazards for travelers and commuters, the TV station said. The city deployed more than 75 snow plows by at noon Friday, increasing the number to 183 at 2 p.m. Ninety-minute delays were reported at O\'Hare International Airport, with more than 300 flights canceled Friday. A total of 6 to 12 inches of snow was expected from the storm, with localized areas seeing 18 inches of lake-effect snow.