When the polar vortex stumbles, the weather at ground level can pivot from mild to brutal in a matter of days. A circulation that usually spins quietly above the pole can suddenly send lobes of Arctic ...

New York is bracing for the coldest air of the winter this weekend, with snow. Learn how the polar vortex is involved.

This winter’s harsh run in the East is intensifying, with some of the coldest air so far this season plunging into Vermont this weekend.