Perilously cold temperatures threatened millions of people in the US in the wake of a winter storm that led to deaths, knocked out power and paralysed transportation.
A life-threatening Arctic air mass could delay recovery as municipalities from New Mexico to Maine tried to dig out following the storm, which dropped a mix of heavy snow and wind along with freezing rain and sleet.
The storm was linked to several deaths, according to a compilation of state government and local media reports, with causes including hypothermia as well as accidents related to traffic, sledding, ATVs and snowplows.
Power returned across the south but as of yesterday evening over 600,000 customers remained without electricity, according to the tracking site Poweroutage.com.
Tennessee, Texas, Mississippi and Louisiana - southern states unaccustomed to intense winter weather and the bone-chilling cold that's forecast to continue for much of the next week - were especially impacted.
Approximately 190 million people in the United States were under some form of extreme cold alert, the National Weather Service (NWS) told AFP.
People living as far south as the Gulf Coast were expected to experience freezing temperatures nightly well into the week.
People in the Great Lakes region woke up to extreme temperatures that could cause frostbite on exposed skin within minutes.
In parts of Minnesota and Wisconsin, the NWS reported early yesterday morning temperatures as low as -30.6C, with windchills exacerbating the bite.
The temperature in those states are set to climb slightly today but still remain extreme.
Over the weekend nearly half of the states in the contiguous US received at least 30.5cm of snow and in many cases far more.
The NWS said New Mexico's Bonito Lake accumulated the highest US total over the weekend with 78.7cm.
Nashville Mayor Freddie O'Connell told journalists that trees were continuing to fall under the weight of encrusted ice across the Tennessee capital city - sometimes knocking out power that had already been restored.
The city's police and fire departments were leading a new task force attempting to connect residents without power with transportation to an emergency warming shelter.
Many other municipalities across the country were establishing similar shelters.
A South Carolina driver, Gary Winthorpe, described to a local news station how he travelled on a treacherous road and witnessed an SUV swerve into a ditch.
"I was pretty scared," he said.
NWS meteorologist Allison Santorelli told AFP this storm recovery was particularly arduous because so many states were impacted - meaning northern states with more winter supplies were unable to share their resources with less-prepared southern regions.
"A lot of those locations don't have the means or the resources to clean up after these events," she said.
"We're particularly concerned about the folks in those areas that are without power right now," she added.
At least 20 states and the capital Washington were under states of emergency in order to deploy emergency personnel and resources.
The snowfall and icy pellets that fell on cities left impassable roads along with cancelled buses, trains and flights - thousands of departures and arrivals were scrapped over the weekend.
The storm system was the result of a stretched polar vortex, an Arctic region of cold, low-pressure air that normally forms a relatively compact, circular system but sometimes morphs into a more oval shape, sending cold air pouring across North America.
Scientists say the increasing frequency of such disruptions may be linked to climate change, but the debate is not settled and natural variability plays a role.
Dave Radell, a NWS meteorologist based in New York, said that the character of this storm's snow was "very dry" and "fluffy", meaning the wind could push it around with ease, impeding roadway-clearing efforts and visibility.
"That makes it even more challenging," he said.
