By Jim Salter | The Associated Press

Vehicles drive on the Rosa Parks overpass at Interstate-5 during a snowstorm on Wednesday, Feb. 22, 2023, in Portland, Ore. (Dave Killen/The Oregonian via AP)

(AP) – Dangerous winter weather trapped drivers on icy roads, knocked out power to hundreds of thousands and grounded multiple flights from California through the northern Plains on Thursday.

For the first time since 1989, the National Weather Service issued a blizzard warning through Saturday for Southern California mountains. Forecasters predicted “multiple rounds of new snowfall” with accumulations of up to 3 to 5 feet (0.91 to 1.5 meters) for the Sierra Nevada region.

Rare snow is also expected over some lower foothills and valley areas near the Pacific Coast, the weather service said, “given the depth of cold air that has infiltrated the West.”

The intense moisture in the air also creates an increased risk of flash flooding through Saturday, forecasters said. Some coastal areas could see waves as high as 10 to 14 feet (3 to 4 meters) through Thursday, forecasters said.

The series of storms sowed chaos from coast to coast. At one point Wednesday, more than 65 million people in more than two dozen states were under weather alerts. The weather service said temperatures in some parts of the upper Midwest could reach 40 degrees below average, while high readings on Thursday in the mid-Atlantic and Southeast could get to 40 degrees above average.

The wintry mix hit hard in the northern U.S., closing schools and offices and forcing churches to call off Ash Wednesday services.

In Wyoming, the state Transportation Department posted on social media that roads across much of the southern part of the state were impassable.

Rescuers tried to reach people stranded in vehicles but high winds and drifting snow created a “near-impossible situation” for them, said Sgt. Jeremy Beck of the Wyoming Highway Patrol.

In the Pacific Northwest, high winds and heavy snow in the Cascade Mountains prevented search teams from reaching the bodies of three climbers killed in an avalanche on Washington’s Colchuck Peak over the weekend.

Unexpectedly heavy snow during afternoon rush hour Wednesday sent dozens of cars spinning out in Portland, Oregon, and caused hourslong traffic jams. The regional bus service offered free rides to warming shelters for homeless individuals.

In Arizona, several interstates and other highways were closed due to high winds, falling temperatures and blowing snow. the Arizona Department of Transportation advised people not to travel. Forecasters said snow could fall at a rate of 2 to 3 inches (5 to 8 centimeters) per hour on Thursday.

In California, a blizzard warning was in effect through Saturday for higher elevations of the Sierra Nevada, where forecasters said conditions could include several feet of snow blown by 60-mph (96-kph) gusts and wind chill could drop the temperature to minus 40 degrees Fahrenheit (minus 40 Celsius).

In Sacramento, the state capital, the weather service said it had received reports of something that might be either hail or graupel — soft, wet snowflakes encased in supercooled water droplets.

Electrical grids took a beating in the north as heavy ice accumulations and gusty winds knocked down power lines. In California, lines were fouled with tree branches and other debris.

In southwestern Michigan, a firefighter in the village of Paw Paw died Wednesday after coming in contact with a downed power line, authorities said. Van Buren County Sheriff Dan Abbott called it a tragic accident that was “no fault of the firefighter.”

More than 681,000 customers were without power in Michigan; over 84,000 in Illinois; over 58,000 in Wisconsin; about 42,000 in California and about 32,000 in New York State as of Thursday morning, according to the website PowerOutage.us.

Weather also contributed to nearly 1,800 U.S. flight cancellations on Wednesday and another 759 by Thursday morning, according to the tracking service FlightAware. Another 6,000-plus flights were delayed across the country.

At Denver International Airport, Taylor Dotson, her husband, Reggie, and their 4-year-old daughter, Raegan, faced a two-hour flight delay to Nashville on their way home to Belvidere, Tennessee.

Reggie Dotson was in Denver to interview for a job as an airline pilot.

“I think that’s kind of funny that we’ve experienced these types of delays when that’s what he’s looking into getting into now as a career,” Taylor Dotson said.

Few places were untouched by the wild weather, including some at the opposite extreme: Long-standing record highs were broken in cities in the Midwest, mid-Atlantic and Southeast.

Nashville topped out Wednesday at 80 degrees Fahrenheit (27 degrees Celsius), breaking a 127-year-old record for the date, according to the weather service.

Indianapolis; Cincinnati; Atlanta; Lexington, Kentucky; and Mobile, Alabama, were among many other record-setters.

No warmup was forecast this week, though, in the northern U.S. More than 18 inches (46 centimeters) of snow could pile up in parts of Minnesota and Wisconsin, the National Weather Service said. According to the weather service, the biggest snow event on record in the Twin Cities was 28.4 inches (72 centimeters) from Oct. 31 through Nov. 3, 1991.

As of Thursday morning, the weather service reported 16 inches (41 centimeters) of snow in the Minneapolis suburb of Savage and 10.1 inches (26 centimeters) at Minneapolis-St. Paul International Airport, with only a little more expected. Many roads remain snow-covered and in some cases closed, it said.

“Thankfully this storm didn’t produce the amounts it had the potential to, but it still produced a lot, and combined with the windy conditions it is simply not safe to travel right now,” the weather service tweeted.

Temperatures could plunge as low as minus 20 degrees Fahrenheit (minus 29 degrees Celsius) Thursday and to minus 25 Fahrenheit (minus 32 Celsius) Friday in Grand Forks, North Dakota. Wind chills may fall to minus 50 F (minus 46 C), said Nathan Rick, a meteorologist in Grand Forks.

Powerful winter weather will make its way toward the East Coast later this week. Places that don’t get snow may get dangerous amounts of ice, forecasters warned.

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Salter reported from O’Fallon, Missouri. Numerous Associated Press reporters from around the country contributed to this report.