A polar vortex is slated to sweep most of the continental US bringing winter storm warnings and a hazardous freeze to millions.

The updated forecast on timing and track of the storm calls for the snow to end from southwest to northeast as midnight approaches. “The heaviest precipitation looks to occur between roughly 4 and 9 p.m. during which time snowfall rates could reach or exceed 1 inch per hour,” the National Weather Service said.

Marc Chenard, a meteorologist with the National Weather Service in College Park Maryland, projected that as many as 70 million residents will be under some kind of winter storm ha