Northern New England may get as much as a half-foot of snow in the next two days as a wave a low pressure and cold air blows in from the U.S. Midwest and Plains.

The storm yesterday dumped 8 inches (20 centimeters) of snow in Farwell, Michigan, said AccuWeather on its Web site. Farwell is 90 miles (145 kilometers) north of Lansing, Michigan.

''Southern New England and the mid-Atlantic region will escape with nothing but rain this time,'' said John Kocet, an AccuWeather meteorologist. ''Just like the snow up north, the rain will come and go over a six- to eight-hour period.''

A second storm that will start with rain in the U.S. Southeast will move into the mid-Atlantic and Northeast tomorrow night, AccuWeather said. The forecast calls for rain to change into wet snow in Philadelphia and New York as night falls, with little accumulation.

To the north of New York City, 3 inches to 6 inches of snow may fall across a swath from the Pocono Mountains to Maine by Dec. 31, AccuWeather said. Boston may break its snowiest December record, set in 1970 when 27.9 inches fell.

More Storms

A winter storm watch is in effect from tomorrow evening through Dec. 31 which covers most of Massachusetts from the greater Boston area west to the Berkshire County line and in Northern Connecticut, the National Weather Service said.

San Francisco International Airport reported delays of 63 minutes today due to low hanging clouds and limited visibility, according to the U.S. Federal Aviation Administration. No other delays were reported.

Yesterday, Chicago's O'Hare International Airport and Midway International Airport canceled more than 450 flights and delays averaged 90 minutes because of the storm, spokesman Gregg Cunningham said in an e-mail. Both runways at Milwaukee's General Mitchell International Airport were closed and two of three runways were closed at Dane County Regional Airport in Madison, Wisconsin, because snow was falling faster than airport attendants could clear it.

The Western U.S. will get ''pounded'' this weekend by several rain and snowstorms, mostly in Northern California, Oregon and Washington, as cold air from Canada pushes snow into areas that normally receive rain, AccuWeather meteorologist Dave Samuhel said.

As much as 3 feet (1 meter) of snow may fall in the Cascade Mountains in Oregon and Washington and the Sierra Nevada in California, Samuhel said.