A collapse in the polar vortex is letting Artic air come here. What that means, and why it happens.

Much of the nation east of the Rocky Mountains is hunkered down for what could be the worst winter storm of the season.

Meteorologists warn that a stretched polar vortex could bring severe winter weather to much of the United States.

Rising Arctic temperatures and melting sea ice could be causing cold air to flow into the Northern Hemisphere. But not all ...

The meteorologists said the polar vortex system is set up due north of Michigan over Canada's Hudson Bay. It's at least ...

Tens of millions of people are in the path of a major winter storm. Federal cuts threaten efforts to understand the causes of such weather.

The sudden blast may come as a shock to many Americans after a mostly mild start to winter, but that warmth may be partly ...

The North Pole is surrounded by a massive circular upper-air weather phenomenon in the Arctic called the polar vortex. It is ...