US storm leaves almost 700,000 without power

More than 670,000 customers in the US as far west as ⁠New Mexico were without electricity and almost 10,000 flights were cancelled ahead of a monster winter storm that threatened to paralyse eastern states with heavy snowfall.

Forecasters said snow, sleet, freezing rain and dangerously frigid temperatures would sweep the eastern two-thirds of the country today and into next week.

Calling the storms "historic," President Donald Trump approved federal emergency disaster declarations in South Carolina, Virginia, Tennessee, Georgia, North Carolina, Maryland, Arkansas, Kentucky, Louisiana, Mississippi, Indiana, and West Virginia.

"We will continue to monitor, and stay in touch with all States in the path of this storm. Stay Safe, and Stay Warm," he wrote in a post on Truth Social.

Seventeen states and the District of Columbia have declared weather emergencies, the Department of Homeland Security said.

DHS Secretary Kristi Noem warned Americans to take precautions.

"It's going to be very, very cold," Ms Noem said. "So we'd encourage everybody to stock up on fuel, stock up on food, and we will get through this together."

"We have utility crews that are working to restore that as quick as possible," Ms Noem added.

The number of outages continued to rise. As of 7.23am EST (12.23pm Irish time), more than 500,000 U.S. customers were without electricity, according to PowerOutage.us, with more than 100,000 each in Mississippi, Texas, and Tennessee. Other states affected included Louisiana and New Mexico.

The Department of Energy issued an emergency order authorising the Electric Reliability Council of Texas to deploy backup generation resources at data centres and other major facilities, aiming to limit blackouts in the state.

It also issued an emergency order to authorise grid operator PJM Interconnection to run "specified resources" in the mid-Atlantic region, regardless of limits due to state laws or environmental permits.

The National Weather Service warned of an unusually expansive and long-duration winter storm that ⁠would bring widespread, heavy ice accumulation ⁠in the Southeast, where "crippling to locally catastrophic impacts" can be expected.

Weather service forecasters predicted record cold temperatures and dangerously cold wind chills descending further into the Great Plains region by tomorrow.

More than 9,600 US flights scheduled for today were cancelled, according to flight tracking website FlightAware, with over 4,000 flights cancelled yesterday.

Major US airlines ⁠warned passengers to stay alert for abrupt flight changes and cancellations.

US electric grid operators stepped up precautions to avoid rotating blackouts.

Dominion Energy, whose Virginia operations include the largest collection of data centres in the world, said if its ice forecast held, the winter event could be among the largest to affect the company.

New York Governor Kathy Hochul warned residents to stay inside amid frigid conditions: "Five or six minutes outside could literally be dangerous for your health."

She stressed precautions like protecting pipes, using heaters safely, and checking on vulnerable neighbours.

Authorities warned of life-threatening cold that could last a week post-storm, especially in the Northern Plains and Upper Midwest, where wind chill lows were forecast to dip to extremes under -45C.

Such temperatures can cause frostbite within minutes.