Weather systems are sweeping across the United States, putting millions at risk of potentially hazardous travel.

A powerful winter storm system moving across the Great Lakes and Northeast is bringing snow and ice, frigid temperatures and possible whiteout conditions.

Snowfall projections have jumped yet again for the major post-Christmas storm, with the latest National Weather Service map now showing up to 8 inches or more in several tristate communities. The newest forecast,

Wayne and northern Cayuga Counties may see 1-to-2 feet of snow, with up to three feet locally. Travel will be “very difficult to impossible in the heaviest bands of snow with near zero visibility and deep snow cover on roads,” says the NWS Buffalo office.

The National Weather Service warns of heavy lake effect snow today in Onondaga, Oswego, Lewis, Jefferson, and northern Oneida counties. Some areas may get over 7 inches, and parts of Oswego could see up to 4 feet of snow.

Snowfall projections have been bumped up for the post-Christmas storm, with a new National Weather Service map showing widespread 5 to 7 inches now likely across much of the tristate area, and even higher totals in some spots.

Here's how much snow Cape Cod - and the rest of Massachusetts - is expected to see, according to the National Weather Service.

Lake effect snow, intense rain and chilly temperatures dominate the forecasts for different parts of the U.S., before and after the new year arrives.

A quick-hitting system will brush the tristate with light snow before a change to rain at the coast, bringing a slick morning commute for some areas.The National Weather Service said the storm’s window runs late Monday,

A clipper storm, as defined by the National Weather Service, is a fast-moving storm that drops into the U.S. over the Great Lakes from Alberta, Canada. According to Peyton Simmers, a meteorologist with AccuWeather, the snow is expected to begin falling on the city around 5 p.m.