UK & World News
Polar Vortex: Deep Freeze Moves Across US
A whirlpool of freezing, dense air known as a "polar vortex" has gripped the US Midwest and is making its way east and south, bringing record low temperatures.
Thermometers plunged to -32C (-25F) in Fargo, North Dakota, while Madison, Wisconsin, hit -28C (-19F) and even Chicago and Minneapolis saw temperatures reach -20F, with wind chills of -50F.
Forecasters say some 187 million people could feel the effects of the frigid blast by the time it has spread across the country.
Nearly 3,200 flights - one out of every 10 domestic departures - were cancelled on Monday, following a weekend of travel disruption across the US.
Airline officials said de-icing fluid was freezing and fuel was pumping sluggishly.
More than a foot of snow has been dumped on a large part of the nation's midsection, forcing officials to close schools in Chicago, St Louis and Milwaukee.
In Chicago, transit officials believe the frigid conditions caused a commuter train to strike a bumping post at a central station, injuring 14 passengers.
Authorities said six people were taken to hospital with minor injuries after the accident - the second such incident of the day.
The National Weather Service (NWS) is predicting 48 US states will have wind chills of below zero - an area of 1.5 million square miles.
Indianapolis Mayor Greg Ballard upgraded the city's travel emergency level to "red" for a time, making it illegal for anyone to drive except for emergencies or to seek shelter.
The last time the city issued such a warning was in 1978.
Utility crews worked to restore power to more than 40,000 Indiana customers affected by the weekend storm and cautioned that some people could be in the cold and dark for days.
In New York City, the temperature was expected to drop sharply from about 11C (52F) to around -12C (10F) as the Arctic air moved in.
Missouri transport officials said it was too cold for rock salt to be effective and several roads in Illinois were closed because of drifting snow.
Government offices and courts in several states have also been closed.
In Newfoundland, Canada, around 30,000 customers remain without power because of rolling blackouts over the last few days.
The record cold temperatures are also affecting southern states.
Louisiana citrus farmers have been warned they could lose any fruit they cannot pick as two nights of freezing temperatures are forecast.
Fans braved subzero temperatures to watch the Green Bay Packers lose 20-23 to the San Francisco 49ers at Lambeau Field on Sunday night.
The game kicked off with temperatures of -15C (5F), making it the seventh coldest NFL game in history.
People in Canada have also been reporting hearing loud "booms" known as "frost quakes"
The phenomenon - or cryoseism - takes place when water underground freezes and then expands, forcing the ground to crack and creating the noise.
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