LOS ANGELES >> California residents evacuated neighborhoods below hillsides scarred by wildfires as the third — and largest — in the latest series of storms brought powerful rain Sunday and warnings about flash flooding and mudslides.

The National Weather Service warned that the system was expected to gain strength throughout the day and could be the strongest storm in at least seven years. Rain and snow have swamped California during a wet winter that has brought relief after years of drought.

Flash flood watches and warnings were in effect for swaths of greater Los Angeles, where mountain locations could see up to 6 inches of rain.

Authorities ordered evacuations near wildfire burn areas in Santa Barbara, Los Angeles and Orange counties. Officials said potential debris flows could restrict access for emergency responders.

Some residents refused to leave, but Ralph Olivas loaded up his family and their dog and left his home in Duarte, nestled in scenic foothills east of Los Angeles that were left bare by wildfires last June. Recent rain sent rocks down steep streets where homeowners built protective barriers out of lumber and sandbags.

“We’re packing and leaving because the muds are coming, the mudslides,” he told Los Angeles news station KCAL-TV, adding that the risk “comes with the territory living up here.”

In northern Los Angeles County, about 120 residents near burn areas of Santa Clarita were ordered to leave late Saturday. During another storm Friday, raging floodwaters overflowed a creek and sent a sheriff’s cruiser floating down a street.

Farther north, strong thunderstorms packing heavy rain and possible hail were expected to hit the San Francisco Bay Area. Wine country communities that already experienced destructive flooding this month faced flash flood warnings. Wind gusts brought down trees across Northern California.

In Mendocino County, a massive oak toppled onto an apartment in the city of Ukiah early Saturday, crushing the building and killing a woman as she lay in her bed, fire officials told the Press Democrat newspaper of Santa Rosa. The woman’s boyfriend and a 3-year-old boy escaped.

Capt. Pete Bushby of the Ukiah Valley Fire Authority said heavy rain apparently had destabilized the 125-foot tree.

Avalanche warnings were in place through Monday across the Sierra Nevada, which was already blanketed with deep snow after weeks of storms. The weather service warned of “crippling snow amounts on top of existing snow cover” and urged mountain residents to stock up on food, water and firewood, and “essentially prepare for being stranded at home for multiple days.”

Along the coast, big surf rolled ashore, with waves that could build to 30 feet on the Central Coast, forecasters said.

Two women were swept from the shore in San Diego, where waves topped 10 feet Saturday. One woman was rescued immediately but it took lifeguards about 40 minutes to pull the other one from the surf. She was hospitalized in critical condition, San Diego Fire-Rescue Capt. Joe Amador said.

Elsewhere in the West, Nevada, Arizona and Utah expected strong winter storms overnight into Monday.