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

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.

The polar vortex is a large area of low pressure and cold air surrounding both of the Earth’s poles. It ALWAYS exists near the poles, but weakens in summer and strengthens in winter. The term “vortex” refers to the counter-clockwise flow of air that helps keep the colder air near the Poles.

Michigan is set for several days of frigid temperatures and heavy lake-effect snow as Arctic air continues its slow march across the eastern U.S.

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?

A polar vortex brings bitterly cold Arctic air into southern Ontario. Here’s what it is and what you can expect.

In the coming weeks, cold air will continue for parts of the U.S. thanks to the influence of the polar vortex.