Have you ever seen a 'steamnado' before? The Texas winter storm caused one to appear over Lake Lewisville on Sunday.

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

As the U.S. prepares to take on another bout of cold weather, the term "polar vortex" is getting thrown around. But what is it?

Temperatures could fall below -20 F across certain parts of North Dakota and Minnesota.

The meteorologists said the polar vortex system is set up due north of Michigan over Canada's Hudson Bay. It's at least partly responsible for the frigid temperatures around the region that contributed this week to a 100-vehicle pileup in southwest Michigan and led the city of Detroit to declare a cold weather health emergency.

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.

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

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