Heavy snow, ice and brutal cold are expected to make this winter storm a potentially life-threatening weather event, stretching across two-thirds of the U.S.

The impending winter storm is set to begin across the south-central U.S. on Friday.

A fresh blast of Arctic air is poised to spill across a wide swath of the United States, and the latest polar vortex map makes clear which regions are most exposed. Forecast models show a sharp southward dip in the jet stream that will funnel frigid air from Canada into the central and eastern states,