Chicago: Icy, snow-covered roads and high winds made travel treacherous Sunday from the Dakotas to Michigan and Missouri as much of the US braced for dangerously cold temperatures that could break records. (VIEW PICS)
A whirlpool of frigid, dense air known as a "polar vortex" was expected to suppress temperatures in more than half of the continental US starting into Monday and Tuesday, with wind chill warnings stretching from Montana to Alabama.
The forecast is extreme: 25 below zero Fahrenheit (31 below zero Celsius) in Fargo, North Dakota, minus 31 F (minus 35 C) in International Falls, Minnesota, and 15 below F (26 below C) in Indianapolis and Chicago.
Wind chills - what it feels like outside when high winds are factored into the temperature - could drop into the negative 50s and 60s. Northeastern Montana was warned Sunday of wind chills up to 59 below zero F (51 below zero C).
"It's just a dangerous cold," National Weather Service meteorologist Butch Dye in Missouri said.
Indianapolis Mayor Greg Ballard upgraded the city's travel emergency level to "red," making it illegal for anyone to drive except for emergency personnel, emergency purposes or seeking shelter.
The last time the city issued a travel warning was during the 1978 blizzard.
Several Midwestern states received up to a foot (30 centimeters) of new snow Sunday.
The National Weather Service said snowfall at O'Hare International Airport in Chicago totaled more than 11 inches (28 centimeters) as of 6 p.m. Sunday - the most since the Feb. 2, 2011, storm.
