Thousands were without power in the Pacific Northwest, Texans were dealing with near-record low temperatures and icy conditions, and large swaths of the rest of the country braced for a mix of hazardous winter conditions from a coast-to-coast winter storm, forecasters said.
The storm was expected to bring heavy snow, significant ice accumulations and dangerously low temperatures to much of the country, including the Plains, the Deep South and the Northeast, into Tuesday.
More than 120 million Americans were under ice storm warnings or winter storm warnings or advisories, the National Weather Service said.
Power failures plagued a number of states on Sunday: More than 50,000 people were dealing with outages in Texas, while about 70,000 people in North Carolina and almost 224,000 in Virginia were without power, according to PowerOutage.us, which aggregates live power data from utilities across the United States.
In northwest Oregon more than 200,000 people were still without power. Crews were working to fix more than 1,200 downed power lines, Portland General Electric said.
Gov. Greg Abbott of Texas on Friday issued a disaster declaration for all 254 counties, citing the impending threat of harsh winter weather, including prolonged low temperatures, heavy snow and freezing rain.
Bill Magness, the head of the Electric Reliability Council of Texas, said the grid operator was experiencing record-high electricity demand as wind chills were expected to reach 10 degrees below zero.
“At the same time, we are dealing with higher-than-normal generation outages due to frozen wind turbines and limited natural gas supplies available to generating units,” Mr. Magness said in a statement on Sunday.
The Texas Department of Transportation warned drivers to prepare for “a marathon of historically cold air” over the next few days that could make driving dangerous.
On Sunday, the department closed sections of I-20 after as many as 25 vehicles, including some eighteen-wheelers, were involved in crashes. On Thursday, six people were killed and dozens were hospitalized in a pileup on icy roads that involved more than 100 vehicles on Interstate 35.
The Emergency Medical Services of Austin said on Twitter that medics would be transporting patients to only the closest hospitals because many roadways were impassable.
The Federal Aviation Administration reported delays of nearly two hours at Seattle-Tacoma International Airport and three hours at Dallas/Fort Worth International Airport because of snow and ice. Dallas Love Field, another Dallas airport, said it had “major cancellations across the board.”
The low temperatures in the middle of the country were expected to approach record lows. In Oklahoma City, the temperature on Tuesday is forecast to be nine degrees below zero. The record low of 17 degrees below zero was set in 1899.
Temperatures in parts of Oklahoma were 40 degrees lower than usual for this time of year, the National Weather Service said. The duration of the cold conditions is also unusual: Oklahoma may experience nine consecutive days of temperatures below 20 degrees, the Weather Service said.
The conditions stem from a strong high pressure system that came from the Arctic Circle, bringing in some of the lowest temperatures parts of the country have experienced in years, said Michael J. Ventrice, a meteorological scientist with IBM.
That allowed for energy to bring a “a very impactful winter storm” from Texas up through the Gulf States from Louisiana all the way up to the Northeast, he said.
After bringing heavy snow across the mountains and lowlands of Washington and Oregon, with significant icing in northwest Oregon on Saturday, the storm was expected to deepen in the Southern Plains, the Weather Service said.
It was expected to shift into the Mississippi, Tennessee and Ohio Valleys and upward into the Northeast through Tuesday, bringing bitterly cold weather, dangerous wind chills and icy conditions.
As the storm runs along the temperature gradient toward the Northeast, it may result in dangerous icy conditions and more power failures across the country, Mr. Ventrice said.
“It’s a huge swath from Tennessee, West Virginia, up to Pennsylvania,” he said. “New York City could be impacted, parts of Boston, Western Mass up into New England, so it’s like, just a massive swath of ice accumulations,” he said.
Most warnings for the storm should expire by Wednesday but Mr. Ventrice warned that another winter storm with a similar path appeared to be “right on its heels” and was expected to form on Wednesday.
“It’ll start over eastern Texas, and making its way up the Southeast and parts of the Middle Atlantic into the Northeast, and there’s going to be another round of wintry weather as well,” he said.