A major winter storm is forecast to spread heavy snow, sleet and dangerous ice to tens of millions of Americans across two dozen states starting on Friday and continuing into the weekend.

Airlines scrapped more than 3,700 flights Saturday while cancellations for Sunday have soared to more than 8,200 due to this weekend's winter storm.

Around 190 million people — more than half the U.S. — are under winter weather alerts across 37 states, from the Rockies to New England.