Much of the nation east of the Rocky Mountains is hunkered down for what could be the worst winter storm of the season.

Meteorologists warn that a stretched polar vortex could bring severe winter weather to much of the United States.

Major cities across the Northeast and Midwest are facing temperatures 10-20 degrees below average, according to forecasters.

A Polar Vortex brought temperatures so cold in January 2014 that it froze Niagara Falls. Signals of a rare sudden stratospheric warming in the next two weeks have some forecasting an imminent Arctic ...