Weather experts track the polar vortex to help forecast coming cold air masses - it's one of the many puzzle pieces that help predict winter storms.
The same polar vortex pattern that struck in early January is happening again this week; only the cold air blanketing the East Coast isn't quite so frigid. But the cold wave will last as long as a week, Oravec said.
"You need a favorable pattern for cold, and the patterns are very similar, it's just the magnitude that's different," Oravec told LiveScience. "It's still pretty impressive cold air, but this one is going to be a little more prolonged."
A shot of cold air came in across the Plains on Tuesday, followed by another Arctic surge on the weekend, Oravec said. Another series of cold air blasts is expected early next week, extending the freeze.
"The temperatures are not quite as cold [as in early January, but the pattern is more persistent in this event," Oravec said.
While Americans living east of the Rockies will shiver this week, the weather will be dry and warm in the West and Alaska. That's because atmospheric flow patterns that are freezing the central and eastern United States and Canada are also contributing to the drought and warm temperatures in the West, Oravec said.