Accidents, some canceled flights and cold temps signaled the arrival of winter Sunday.

The storm caused traffic problems Sunday evening, and with the possibility of more snow and freezing temperatures for the next few days, driving could remain dangerous.

By about 11:30 p.m. Sunday, the Dane County Sheriff's Department said snow had caused at least a dozen slideoffs, but only one with possible injuries.

The worst conditions were to the south and east of Dane County, the State Patrol said, reporting multiple slideoffs but no serious injuries or blocked roads. Areas around Milwaukee were forecast to receive heavy snow. The state opened its Emergency Operations Center on Sunday afternoon.

The National Weather Service, which issued a winter storm warning, predicted up 2 to 4 inches of snow to hit the Madison area by early Monday morning. More light snow is possible during the coming days.

The weather forced cancellation of flights between Chicago's O'Hare airport and Dane County Regional Airport Sunday night, director of operations John Robinson said.

The Dane County airport was "open for business" but bad weather in Chicago caused cancellations, Robinson said.

The storm heralded the annual ritual of drivers recalling how to navigate icy roads. Having the first storm arrive on a key shopping and travel day at the end of a holiday weekend was unlucky timing.

"It takes a little while to remember winter driving," said Ravi Balijepalli, who was shopping for a snowblower, ice scraper and other supplies at Home Depot on Madison's Southwest Side with his wife, Sadguna.

"We took a peek at the weather and we are not yet ready, so that's why we're here," he said. The couple are originally from India and moved to Madison nine years ago, but it took the record-breaking snowfall last year to convince them to buy a snowblower this season.

Also shopping for a snowblower was Kim Schultz, who was not enthused by the snow.

"I am not ready for winter — I despise winter; I abhor winter," Schultz said. "I have to leave tonight on a business trip and my wife said I had to get a snowblower before I go. So maybe after today I'll be physically ready for winter, but emotionally, no."

Tiffany Dixon, who moved to Madison six years ago from Florida, wore a coat to shop at Burlington Coat Factory, but after a bad winter last year, she was looking for an even warmer coat and more warm clothes. "I felt like I was shoveling all the time, every day," Dixon said. "I hope we have a better winter than last year."

The AAA Wisconsin auto club predicted 6.2 million people would travel at least 50 miles by car in the Great Lakes region for the holiday weekend.

The snow, combined with heavy road travel due to the end of holiday weekend, shoppers and a home Packers' game, had law enforcement ready to add staff, said Sgt. John Wolfe at the State Patrol's DeForest headquarters.

State Journal reporters Melanie Conklin and Dean Mosiman contributed to this article.