The slow-moving storm that parked itself over the region on Monday, dumping 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.

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 over the span of days.

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.