A massive winter storm named fern is set to sweep across much of the United States, bringing snow, ice and extreme cold. Over 230 million people could be affected, with major travel and power disruptions expected.

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,

People across a large section of the central and eastern United States are facing predictions of heavy snow and ice starting Friday.