As polar vortex lingers, parts of U.S. set for record lows

Parts of the United States are bracing for record low temperatures on Wednesday, as a blast of Arctic air gripping much of the country spreads further across the Midwest and Eastern states.
Temperatures could hit minus 40 Fahrenheit (minus 40 Centigrade) in parts of the Northern Plains and Great Lakes, the National Weather Service said.
"The heart of this cold... is hitting us now. A lot of records are going to fall," said Brian Hurley, a meteorologist with the NWS's Weather Prediction Center in Maryland.
With officials in Illinois and the Northern states advising residents to stay indoors, dashcam footage from one trucker taken outside Grand Rapids, Michigan gave a snapshot of hair-raising driving conditions.
"I about just got caught in a giant wreck; cars are into other pickups, there's people hurt. I gotta let you go." Jason Coffelt is heard saying in an Instagram posting dated Tuesday, as his truck is forced off the highway and pulls up just before a multi-vehicle accident.
In neighboring Illinois, Chicago was bracing for one of its coldest days on record.
Almost 2,000 flights were canceled early Wednesday, largely out of Chicago O'Hare and Chicago Midway international airports, the flight tracking site FlightAware.
Train service Amtrak said it had canceled all trains in and out of the city, where Hurley forecast minus 15 Fahrenheit on Wednesday and a record-low minus 27 on Thursday.
The bitter cold is being carried by the polar vortex, a stream of air that spins around the stratosphere over the North Pole, but whose current has been disrupted and is now pushing south.
Including the wind chill factor, parts of the Dakotas, Wisconsin and Minnesota could see life-threatening temperatures as low as 70F below zero on Wednesday, forecasters said.