Record-breaking storm launches debris through Los Angeles area, leaves hundreds of thousands without power

A storm of historic proportions unleashed record levels of rain over parts of Los Angeles on Monday, sending mud and boulders down hillsides dotted with multimillion-dollar homes, posing grave dangers to the city's large homeless population and knocking out power for more than a million people in California.

About 710,000 people statewide were without power Monday evening.

The storm was the second one fuelled by an atmospheric river to hit the state over the span of days.

Virtually all of Southern California was under flash flood advisories and watches, including the Los Angeles area, where between 12.7 to 25.4 centimetresof rain had fallen and more was expected, according to the National Weather Service.

So far officials have attributed three deaths to the storm that first hit Northern California. Crews were rescuing people from swift-moving water in various parts of Southern California on Monday.

Residents scramble for shelter

Among those rescued were two homeless people who spent the night on a small island in the Santa Ana River in San Bernardino, about 88.5kilometreseast of Los Angeles, authorities said.

"They were cold and exhausted from a night out stranded on this little patch of dirt that was in the middle of the river," said Capt. Nathan Lopez of the San Bernardino County Fire Department.

At a news conference, authorities said rain would taper off in intensity on Tuesday, but the threat of flooding remained high.

"The ground is extremely saturated, supersaturated," said Ariel Cohen, meteorologist in charge of the National Weather Service bureau in Los Angeles.

"It's not able to hold any additional water before sliding. It's not going to take much rain for additional landslides, mudslides, rockslides and other debris flows to occur."

Near the Hollywood Hills, gushing rivers carried mud, rocks and household objects downhill as floodwaters coursed through Studio City, damaging at least two homes, city officials said. Sixteen people were evacuated.

"It looks like a river that's been here for years," said Keki Mingus, whose neighbours' homes were damaged. "I've never seen anything like it."

The Los Angeles Fire Department said 1,000 firefighters were contending with 49 debris flows, 130 reports of flooding, half a dozen structure fires and several rescues of motorists stranded in vehicles.

Drake Livingston, who lives in the Beverly Crest neighbourhood of Los Angeles, was watching a movie around midnight when a friend alerted him to flooding.

"We looked outside and there's a foot-and-a-half of running water, and it starts seeping through the doors," Livingston said.

Livingston scrambled to save the studio equipment downstairs and other items, but eventually had to retreat to a neighbour's house. In the morning, Livingston's car was submerged in mud as were other vehicles.

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Record rainfall in Los Angeles

Los Angeles Mayor Karen Bass urged residents to avoid driving, warning of fallen trees and electrical lines on flooded roadways.

It was already the third wettest two-day period on record in downtown Los Angeles as of Monday afternoon and some was still coming down, said Dave Bruno, meteorologist with the local branch of the National Weather Service. The area was also on par to get about half its annual rainfall in one storm. The service has been keeping records in downtown since 1877.

"This is something that will be remembered, just based on numbers, for a while," Bruno said.

Shelters were adding beds for the city's homeless population of nearly 75,000 people.

Tony Sanz spent the night in a city park before seeking higher ground around dawn as floodwaters were rising around his tent.

"Boy did it rain last night," he said Monday afternoon whilehunkered down in a tent layered with tarps on a sidewalk outside a supermarket. He spied the cloudy skies during a break in the downpours and wondered, "Is that it? I hope that's it."

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What is an atmospheric river?

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Duration 1:23

It's a term that became more widely known after record-setting flooding hit B.C. in November 2021, but as meteorologist Johanna Wagstaffe explains, atmospheric rivers are not new to west coast of North America.

Not yet, according to forecasters

The weather service forecast up to 20 centimetresof rainfall across Southern California's coastal and valley areas, with 35 centimetrespossible in the foothills and mountains over the next two days.

At a news conference Monday, authorities reported several spills, including the discharge of about fivemillion gallons of raw sewage in the Rancho Dominguez area surrounding Compton. Most of the untreated sewage went into a channel leading to the Pacific Ocean and the city closed an 11-kilometrestretch of Long Beach to recreational swimming,

City's train station flooded

Earlier in the day, commuters stepped through several inches of floodwater as they rushed to catch trains at Union Station in downtown Los Angeles.

Most Los Angeles public schools remained open but some districts were closed. The weather also prompted a rare early closure of Disneyland.

In Yuba City, about 160 kilometresnortheast of San Francisco, police said they were investigating the death of a man found under a big redwood tree in his backyard Sunday evening.

Gov. Gavin Newsom declared a state of emergency for most of coastal Southern California, while emergency shelters were opened.

Off the coast of Long Beach, 19 people were rescued Sunday after the 40-foot sailboat they were travelling in lost its mast amid gale-force winds, said Brian Fisk of the Long Beach Fire Department.

Heavy snow was falling throughout the Sierra Nevada and motorists were urged to avoid mountain roads.

Much of the state was still drying out from the initial atmospheric river-powered storm that blew in last week. Atmospheric rivers are relatively narrow plumes of moisture that form over an ocean and can produce torrential amounts of rain as they move over land.

Both atmospheric rivers were called a "Pineapple Express" because they originated near Hawaii.

Since last winter, 46 atmospheric rivers have made landfall on the U.S. West Coast, pulling the state out of a years-long drought, according to the Scripps Institution of Oceanography's Center for Western Weather and Water Extremes. Nine were categorized as strong, two were extreme and one was exceptional.