The Upper Midwest and Northern Plains have been hit by Canada's freezing temperatures. On Thursday, Dec. 4, wind chills between negative 10 to negative 25 degrees will be expected, and the cold temperatures are expected to continue into Friday, Dec. 5 for those in the eastern U.S.

A polar vortex broke, and severe temperatures are set to dominate most of the United States, including the Midwest, in the coming days.

Year-round, severe, artic air is usually kept tightly contained in the North Pole. Arctic wind patterns create a sort of wall around the pole that prevents frigid air from trickling southward. That wall that keeps cold air contained is called polar vortex.

Polar vortex disturbance is causing frigid Artic air to surge southward, bringing cold temperatures and possibly snow to many regions of the US.

The culprit behind the country’s somewhat wacky weather, or at least part of it, is the (aforementioned) probable sudden stratospheric warming event (SSW) disrupting the stratosphere’s polar vortex over the Arctic. When this happens, frigid air from the stratospheric polar vortex is displaced to the mid-latitudes via the polar jet stream.

A strong polar vortex doesn't cause cold weather — it does the opposite. Here's what to know about polar vortices, how they work.

In yet another sign that winter weather is either here or will be soon, the dreaded polar vortex is making news yet again. Its potential arrival in the United States over the next few weeks is cause for nervous anticipation among both cold weather lovers ...

High above the North Pole, about 10 to 30 miles above Earth’s surface, sits a massive whirlpool of icy air known as the polar vortex. Think of it as a giant spinning top of frigid air trapped by strong winds in the stratosphere.