SAN DIEGO − The tail end of a powerful atmospheric river storm that knocked out power to hundreds of thousands of California homes and businesses was deluging the state Monday with more heavy rain, mudslides, flooding and several feet of snow in the mountains.

In Southern California, the heavy winds that blasted the region Sunday were diminishing, but the National Weather Service warned that an unstable weather pattern could generate waterspouts or small tornadoes.

Flash flooding "is a much greater threat than any weak tornado that the storm may spawn," the weather service said, and dangerous flooding was likely across much of the region from the atmospheric river − the equivalent of a river in the sky that is responsible for extreme rain and snow in the West.

Additional rainfall totals of 5-8 inches were forecast in some areas, which would bring 48-hour totals as high as 14 inches for some locations, the weather service said. A state of emergency was declared in eight Southern California counties.

"Life-threatening conditions may evolve extremely fast in some communities," AccuWeather Senior Meteorologist Alex Sosnowski warned.

In San Diego, Mayor Todd Gloria issued an evacuation warning for low-lying, flood-prone areas that were battered by heavy rains last week and flooded out two weeks ago. Some areas outside the city saw up to 7 inches of rain in the last two days.

"I understand the weariness that must come from these repeated warnings," Gloria said. "I recognize that fatigue may be settling in. But I can assure you this decision to issue this warning is not taken lightly. I ask that everyone remain prepared and viligant."

Developments:

∎ Los Angeles recorded more than 4 inches of rain Sunday, breaking the record for the day by more than an inch. It was the most rain in one day in more than 20 years, and surpassed the average for the month of February.

∎ The AT&T Pebble Beach Pro Am golf tournament in Monterey County, which had postponed Sunday's final round to Monday, canceled play Monday and declared Wyndham Clark the winner despite playing only 54 holes of the scheduled 72-hole tournament.

∎ In Yuba City, 40 miles north of Sacramento, a man was killed when a redwood tree toppled on him in high winds, police said.

Climate change, El Nino conspire to fuel storms

Multiple weather phenomena are conspiring to make these storms particularly damaging. Warm water provides energy to storms, and record-high ocean water temperatures, likely from climate change, are being detected around the world. Additionally, the Pacific Ocean is also seeing the effects of a more localized El Nino, where weakening trade winds reduce the upwelling of ocean waters and allow surface waters to bake in the sun and grow warmer still. And California, coming off years of drought and wildfires, is particularly vulnerable to mudslides and flooding.

"The atmospheric river firehose is aimed at Los Angeles," tweeted Meteorologist Ryan Maue. "The onslaught has just begun from this treacherous bomb cyclone."

102-mph wind gust recorded in San Francisco Bay area

In Northern California, the storm swamped streets and toppled trees and power lines across the San Francisco Bay area. A rare hurricane-force wind warning had been posted for the area, and winds exceeded 60 mph with wind gusts recorded as high as 102 mph in Marin County − the equivalent of a Category 2 hurricane.

In nearby San Jose, first responders went door-to-door warning residents of the flood threat and removing unhoused people from riverbeds. They pulled travelers out of the windows of a car stranded by floodwaters and rescued several people and dogs from an island in the Guadalupe River as it became overwhelmed by high waters.

United States Weather Alerts

Storm is second to blast state in days

The storm slammed California just days after much of the state was soaked with up to 6 inches of rain by the first storm in the "Pineapple Express," so-called because moisture builds up in the tropical Pacific around Hawaii and can roll across the ocean and pound the U.S. and Canada's west coasts with heavy rainfall and snow. The current storm is packing more moisture and overwhelming already-saturated regions.

Gov. Gavin Newsom's office said the state had a record number of emergency assets responding to the "serious storm with dangerous and potentially life-threatening impacts." Those impacts included almost 600,000 homes and businesses without power Monday.

Life-threatening flood threat:Heavy rain and powerful winds clobber California

Landslide hits Hollywood Hills

In the Hollywood Hills the weather serviced warned Monday of an "extremely dangerous situation unfolding" with life threatening landslides and flash flooding. Several families had to evacuate when a mudslide caused a gas leak. A neighborhood in Studio City was forced to evacuate after a slide severely damaged multiple homes. In suburban Tarzana, three homes were swamped by debris flow with firefighters aiding the evacuation of residents.

Flooding and small mudslides were also reported across Santa Monica, West Hollywood, Malibu and Beverly Hills.

 “Life-threatening flash flooding is ongoing and will continue into the morning hours of Monday,” the weather service said.

Los Angeles County Supervisor Lindsay Horvath urged residents near wildfire burn areas of Topanga and Soledad canyons to get out ahead of possible mudslides. The county set up shelters for evacuees.

“If you have not already left, please gather your family, your pets, your medications and leave immediately,” Horvath said at a Sunday briefing.

Contributing: The Associated Press