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.

A chilling polar vortex is set to bring snow and ice to the South and East this week. We show where.

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

Large swaths of the United States will get an arctic blast this week, leading to heavy snow, sleet, and freezing rain in parts of the country. Here’s what that means for travelers.

WASHINGTON (AP) — Warm Arctic waters and cold continental land are combining to stretch the dreaded polar vortex in a way that will send much of the United States a devastating dose of winter weather later this week with swaths of painful subzero temperatures, heavy snow and powerline-toppling ice.

The big winter (and popular) topic is dusted off very early this season as frigid air plunges south next weekend. But what is the Polar Vortex, exactly?

That is the polar vortex. It’s not a snowstorm by itself. Instead, it’s a large area of low pressure and cold air that circles the North Pole. It exists all the time, but it usually gets stronger in winter.

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