Another Polar Vortex? What To Expect As 'Dangerous' Winter Weather Descends On US

A mass of frigid air moving down from the north will plunge much of the U.S. into Arctic conditions this week, with the cold rivaling that experienced during last year's so-called polar vortex. The winter déj vu is expected to bring freezing temperatures - in some areas, as low as 40 degrees Fahrenheit below zero - to nearly every corner of the country east of the Rocky Mountains as well as snarling snow and strong winds to parts of the Northwest and Northeast.