Blizzard conditions and heavy snow are threatening tens of millions of people across the central and eastern United States, with winter storms putting a long stretch of Midwest-to-Northeast highways at risk of dangerous whiteouts and ice.

In a post early Friday, the Weather Prediction Center (WPC) said the "significant" winter storm would develop on Friday, bringing with it a "broad area of moderate to heavy snow" from the eastern Plains and through the western Great Lakes area.

Thanksgiving in Iowa was sunny but colder than normal, with morning temperatures in the teens and highs in the mid-30s. A strong winter storm will bring heavy snow starting Friday afternoon, spreading across most of the state and making travel difficult.

A Michigan winter storm could bring up to 20 inches of snow to parts of the state, say National Weather Service snowfall accumulation predictions.

According to the map, shared with Newsweek on Saturday, areas that could see between six and 12 inches of snow include parts of South Dakota, southern Minnesota, the majority of Iowa, northwest Missouri, central and southern Wisconsin, as well as portions of Illinois, Indiana, and Michigan.

A winter storm watch has been issued for the Yankton area for much of Friday through Saturday evening. According to the National Weather Service, the watch is in effect from noon Friday through midnight late Saturday night. Heavy snow of 4-7 inches is possible with the storm system. However, winds are not forecast to be strong.