MINNEAPOLIS - A whirlpool of frigid, dense air known as a "polar vortex" is descending into much of the U.S., pummeling parts of the country with a dangerous cold that could break decades-old records.
For a big chunk of the Midwest, the subzero temperatures are following heavy snow and high winds. Officials have closed schools in cities including Chicago, St. Louis and Milwaukee and warned residents to stay indoors and avoid the frigid cold altogether.
The forecast is extreme: 32 below zero in Fargo, N.D.; minus 21 in Madison, Wis.; and 15 below zero in Minneapolis, Indianapolis and Chicago.
Wind chills could drop into the minus 50s and 60s.
It hasn't been this cold for almost two decades in many parts of the country.
For the tens of millions of Americans currently trapped in the deep freeze: It's not the cold, it's the wind.
Air temperatures plunging into the negative teens, twenties and even thirties Sunday into Monday are bad enough. But add wind speeds of even a few miles per hour, and what's already deeply unpleasant becomes downright dangerous.
Severely low wind chills are a serious threat to the body. Emergency room doctor Douglas Brunette from Hennepin County Medical Center in Minneapolis says he's "seen frostbite occur through clothing." He says it's important to have clothes "made for the elements."
Watch an AP video report below (mobile users: http://bit.ly/1lxvBUt):