The polar vortex is a large area of cold, spinning air that sits near the North Pole and exists year-round. When it weakens or shifts, Arctic air can spill south, increasing the risk of snow and ...

Add Yahoo as a preferred source to see more of our stories on Google. Much of the nation east of the Rocky Mountains is hunkered down for what could be the worst winter storm of the season, followed ...

This winter’s harsh run in the East is intensifying, with some of the coldest air so far this season plunging into New York this weekend as a mass of Arctic air drops south from Canada. "A brutally ...