BOSTON - Motorists slid off roads in the Great Lakes states and in New England yesterday as a storm already blamed for three deaths cut visibility and iced over highways with a brew of snow, sleet and freezing rain.

The National Weather Service posted winter storm warnings from Michigan and Indiana all the way to Maine. Nearly a foot of snow had fallen on the Chicago area and 10 inches in parts of Michigan and Vermont. Meteorologists said 18 inches could fall in northern New England and up to 14 inches in parts of Michigan.

Visibility in the blowing snow was less than 200 yards, said Maine State Police Sgt. Andrew Donovan, and in stronger gusts, "if there's a car in front of you, you can't even see it."

Slippery roads were blamed for two traffic deaths in Michigan and one in Wisconsin.

Every available plow truck was at work in Vermont, said Reggie Brown, highway department dispatcher in Montpelier. Illinois Department of Transportation spokesman Mike Claffey said 1,000 trucks were out clearing snow.

The storm forced cancellation of hundreds of flights at airports in Chicago. Many flights were canceled at airports in the Northeast, including in Portland, Maine; Buffalo; and Manchester, N.H. Few major problems were reported at airports in Philadelphia, Boston and New York, although New York's Kennedy and New Jersey's Newark Liberty reported delays.