More than 160 million Americans are expected to face an unusually brutal winter storm from Friday, with heavy snow and freezing rain.
The storm is expected to sweep across much of the United States, leaving “extremely dangerous” conditions in its wake as it tracks eastward from the High Plains and Rockies, the National Weather Service (NWS) said.
It warned that the Arctic blast would bring sub-zero temperatures and wind chills, which “present a life-threatening hypothermia and frostbite on exposed skin”.
US transportation officials, including airport authorities in several major cities, are warning of weekend travel disruptions, delays and cancellations.
The winter storm is forecast to move slowly across the US, blanketing cities including Memphis, Nashville, Washington DC, Baltimore, Philadelphia and New York with snow.
Heavy snow is forecast across the Southern Rockies and Plains, into the Mid-Atlantic and into the Northeast.
According to the NWS Probabilistic Precipitation Portal, regions that could see more than a foot of snow range from Colorado to West Virginia to Boston.
Several low temperature records are likely to be broken, according to the NWS, with the coldest wind chill possibly dropping below -50F (-46C) across the Northern Plains.
A wider area of the southeastern US is also forecast to experience freezing temperatures.
The governors of several US states, including Arkansas, Georgia, Texas, North Carolina, South Carolina, have declared states of emergency, allowing emergency officials – including National Guard troops – to begin mobilizing response efforts.
Some airlines offer passengers the option to change their flights, in some cases at no extra charge, due to concerns about cancellations.
Motorists should avoid driving over the weekend, with travel expected to be “almost impossible during the peak of the storm”, NWS meteorologists Rich Otto and Tony Fracasso told the BBC’s US news partner CBS.
In Canada, freezing temperatures are already gripping the country, with snow expected in the eastern and Atlantic regions on Monday, meteorologist Geoff Coulson told the CBC earlier in the week.