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.

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?

A polar vortex is expected to bring two surges of extremely cold air to the U.S. in January. Here's what to know in Middle Tennessee.

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

Starting Thursday, dangerously frigid air from Siberia and the North Pole is forecast to plunge the Great Lakes region into subzero territory for multiple days.

What is the polar vortex? This article explains what a polar vortex is in simple terms, how it influences winter weather in the U.S., and why meteorologists talk about it during major cold events.

As a winter storm approaches Western North Carolina and other regions, here's what to know about deciphering forecaster terms.

What is the polar vortex? Mississippi weekend weather forecast calls for winter storm with lows in the teens, paired with freezing rain, sleet and snow.

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

Alabama braces for another polar vortex blast bringing well below freezing temperatures. How cold will temperatures get? Here's what to know.