LOS ANGELES — Rainfall from one of the wettest storms in Southern California history was easing Tuesday after Los Angeles was bombarded with nearly half of its seasonal rainfall in just two days, but forecasters warned of a continuing threat for potentially deadly landslides on super-soaked ground.

The slow-moving storm that parked itself over the region on Monday, dumping a record amount of rain on parts of Los Angeles, could linger into Wednesday, the National Weather Service said. Scattered showers and some possible thunderstorms would bring light to moderate rain, but there was still the threat that many places could see brief, fierce downpours dumping a half-inch to an inch (1.3 to 3 centimeters) of rain in an hour.

Authorities warned people to remain on high alert and most of Southern California remained under flood watches. Swollen and fast-moving creeks and rivers “increase the risk for drowning and the need for swift water rescues,” the weather service said.

Storm Impact

The storm plowed through Northern California over the weekend, killing three people who were crushed by falling trees, then lingered over the south. It was the second storm fueled by an atmospheric river to hit the state in a short span.

On Monday, it deluged Los Angeles with rain, sending mud and boulders down hillsides dotted with multimillion-dollar homes while people living in homeless encampments in many parts of the city scrambled for safety.

Near the Hollywood Hills, floodwaters carried mud, rocks, and household objects downhill through Studio City, city officials said. Sixteen people were evacuated and several homes were red-tagged.

“It looks like a river that’s been here for years,” said Keki Mingus, whose neighbors’ homes were damaged. “I’ve never seen anything like it.”

Drake Livingston who lives in the Beverly Crest neighborhood, 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,” said Livingston, whose car was found submerged in mud Monday morning.

Record Rainfall

Downtown Los Angeles received nearly 7 inches (18 centimeters) of rain by Monday night, nearly half the yearly average of 14.25 inches (36 centimeters). It was already the third-wettest two-day period since 1877, the service said.

The danger wasn’t over despite a projected dip in the rainfall, warned Ariel Cohen, meteorologist in charge of the National Weather Service bureau in Los Angeles.

“The ground is extremely saturated, supersaturated,” he said at a Monday afternoon news conference. “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.”

Rainfall amounts on Tuesday “are not going to be quite as heavy as they have been, but still with the ongoing flooding, any additional rain is not welcome,” National Weather Service forecaster Bob Oravec said early Tuesday.

More showers are possible Wednesday and Thursday, Oravec said. “So it doesn’t look like it’s going to be totally in the clear probably until Thursday and into Friday,” he said.

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Evacuation and Rescue Efforts

In the Los Angeles area, an evacuation order remained in place for some residents of a canyon area that was scarred by a 2022 fire. The area was at increased risk of mud and debris flows because the area was burned bare of brush and trees that could hold it back, authorities said.

The Los Angeles Fire Department said 1,000 firefighters had dealt with more than 300 mudslides in addition to more than 100 reports of flooding and rescues of motorists stranded in vehicles on inundated roadways.

Shelters added 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 hunkered 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.”

Crews rescued people from swift-moving water in various parts of Southern California, including 16 people and five cats in Los Angeles County alone, authorities said.

About an hour’s drive east of Los Angeles, two homeless people were rescued Monday after spending the night on a small island in the Santa Ana River in San Bernardino.

“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. A dog and two cats were also saved.

Environmental Impact

Authorities also reported several spills Monday, including the discharge of about 5 million gallons (18.9 million liters) 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 a 7-mile (11-kilometer) stretch of Long Beach to recreational swimming,

Over the weekend, the storm inundated streets and brought down trees and prompted water rescues in the San Francisco Bay area.

Among those who died were two men killed by fallen trees Sunday in Carmichael, a suburb of Sacramento, and in Boulder Creek in Santa Cruz County. Police were investigating the death of another man in Yuba City, about 100 miles (160 kilometers) northeast of San Francisco, who was found under a redwood tree in his backyard Sunday.

State of Emergency

Gov. Gavin Newsom declared a state of emergency for most of coastal Southern California and on Monday, President Joe Biden promised to provide any needed federal help.

“We’ll get any help on the way as soon as you guys request it,” he told Los Angeles Mayor Karen Bass in a telephone call.