A coast-to-coast storm that paralyzed roads and blacked out nearly 1 million homes and businesses was set to pound California on Friday, sparking warnings about floods and blizzards.

The National Weather Service warned of a “cold and dangerous winter storm” through Saturday. As much as 5 feet of snow could fall in some mountains near Los Angeles, which could create whiteout conditions as winds gust to 75 mph and an increased risk of avalanches, forecasters said.

The weather service issued rare blizzard warnings for Southern California mountain areas and urged drivers to avoid dangerous roads.

Storms already have battered the Plains states and northern regions of the country for days and the National Weather Service predicted continuing problems from ice, snow and freezing rain into the weekend.

In the Pacific Northwest, much of Oregon’s largest city was shut down after almost a foot of snow fell unexpectedly. It took drivers in Portland by surprise, stalling traffic during the Wednesday evening rush hour and trapping motorists on freeways, some of whom spent the night in their cars.

Maia Foley-Weintraub’s 5-year-old son had to spend the night at daycare because she was stuck in snow-stalled traffic for nine hours. In a moment of panic during that time, her van slid down an icy hill, forcing her to use the emergency brake. It took her until 2 a.m. Thursday to make it home safely.

“People were just spinning out and getting stuck left and right,” she said. “It was just one thing after another. I did not have any idea that that was going to turn out the way it did.”

The snow began to melt later in the day but as temperatures dropped and night fell, roads became slick with black ice.

Portions of Interstate 80 in California and Wyoming were closed because of impassable conditions. That included about a 70-mile  stretch over the top of the Sierra Nevada linking California and Nevada.

The weather also knocked out power to nearly 1 million homes and businesses in multiple states and closed dozens of schools. Weather also contributed to airport snarls. At one point on Thursday, more 2,000 flights were grounded and nearly 14,000 were delayed across the country, according to the tracking service FlightAware.com.

Widespread Power Outages

Widespread power outages were reported in Michigan, Illinois, California, New York and Wisconsin, according to the website PowerOutage.us.

The largest outages by far were in Michigan, where at one point more than 820,000 customers were without electricity, mostly in the state’s southeast corner. Some 3,000 power lines were knocked down after being coated with ice as much as three-quarters of an inch thick and crews were struggling to get the juice back by the end of Sunday, utilities said.

“Utilities across the country fear ice storms like we fear nothing else,” said Trevor Lauer, president of DTE Electric. “We’ve not had an ice storm in the last 50 years that has impacted our infrastructure like this.”

A Michigan firefighter died Wednesday after coming in contact with a downed power line in the village of Paw Paw, authorities said.

Winter storm warnings remained in effect in northern Michigan and parts of New England could see sleet, snow and freezing rain as a cold front stretched from the eastern Great Lakes to East Texas, the National Weather Service’s Weather Prediction Center said.

But the weather front was creating vastly different conditions in different parts of the country.

“Southerly flow ahead of the front is creating mild and warm conditions for much of the Southeast and Mid-Atlantic while northwesterly winds behind the front are pushing cold arctic air into the Plains and Upper Midwest,” the weather service said.

Usually balmy California saw unusual winter weather.

Karen Krenis was driving to a pottery studio in Santa Cruz in the San Francisco Bay area on Thursday when she stopped in her tracks after seeing snow on the beach. She got out of her car and went to take photos. By the time she left, about 50 other people were there. Adults were snapping photos, and children were making snowballs.

“I have lived in California for 30 years, and I’ve never seen anything like it,” Krenis said.

In Southern California, the storm began moving Thursday with widespread rain and some snow flurries. There was even a dusting of snow or graupnel — a sort of soft hail — Thursday morning in the hills near the Hollywood sign, although it quickly vanished.

Flood watches and warnings were in effect through Saturday afternoon for some coastal regions and valleys, and the potential for heavy rainfall causing flooding and debris flow in some areas burned by wildfires in recent years.

Evacuation warnings also were issued in Ventura County for four areas that were considered unstable after being hit hard by storms last month.

The weather service said temperatures could drop far below normal in the region. That posed a special risk to thousands of homeless people, with shelter space limited and freezing temperatures expected in some areas.

Terry Stephens, who lives in a trailer with her son and his girlfriend in Palmdale, was temporarily placed in a hotel room in the Antelope Valley city northeast of Los Angeles after shivering through the night on Wednesday.

“It was frigid; your bones ache and you can’t get warm,” she told the Los Angeles Times. “I had three blankets on me last night and I was still freezing. Nothing helped.”