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.

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

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

It exists all the time, but it usually gets stronger in winter. When the jet stream (a river of wind) bends and dips south, the edge of the polar vortex can wobble or stretch. That can let Arctic air slide into the United States and Canada and bring a short spell of extreme cold.

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?

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.

An Extreme Cold Warning starts overnight as an Arctic front will bring the coldest weather the Chicago area has seen since 2019.