LOS ANGELES — Rescuers pulled motorists from swamped cars and found hikers trapped by a swollen creek, as Pacific storms dumped more rain Tuesday on saturated California and forecasters warned of a likely intensification before it all ends.

The storms have affected almost the entire state since they began Friday, dumping moisture from far Northern California south to San Diego. More than 12 inches of rain have fallen in parts of the Santa Monica Mountains in the south, and 13 feet of snow has accumulated at Mammoth Mountain ski resort.

Downtown Los Angeles had received 5.77 inches of rain since Friday, more than a third of the average annual precipitation.

The National Weather Service predicted an even fiercer storm would roll into Southern California beginning Tuesday night. Forecasters warned of possible rainfall rates of .75 inch to 1 inch an hour and thunderstorm rates of 2 inches an hour in the region.

"These rates will pose a significant flash-flooding threat for the recent burn areas and maybe even for the non-burn areas," the National Weather Service said, referring to areas scarred by wildfires.

A swath of Los Angeles suburbs along the foothills below the steep San Gabriel Mountains are at risk of debris flows — potentially devastating flash floods carrying boulders, trees and soil — after a 2009 wildfire that stripped vegetation off 250 square miles of Angeles National Forest. More than 40 homes in the foothills were damaged or destroyed during a February storm.

Geologist Susan Cannon said remote monitoring sites in the Station Fire burn area were picking up the beginnings of a debris flow about three feet deep a mile up the Arroyo Seco, a watercourse that flows out of the mountain range.

The flow consisted of rocks, mud and vegetation, she said.

If the next wave of the storm creates rainfall of an inch an hour or more, the area could be in danger of a significant mudslides or debris flow, said Cannon, who has studied the risk of a slide at the Station Fire site extensively as an employee of the U.S. Geological Survey.

"It means that once the heaviest rains start, it should be a very active time up there," she said.

At the eastern end of the San Gabriels, 15 people were evacuated from four homes in Wrightwood when water and debris crested the bank of a wash. Bulldozers were called to divert water but one home had minor damage. Crews on Tuesday continued working on the wash in anticipation of more rain, San Bernardino County fire spokeswoman Tracey Martinez said.

At least five people were rescued from cars trapped in swift-moving waters on flooded roads in San Bernardino County, said Sheriff’s Department spokeswoman Cindy Bachman. Some had driven past barriers closing off the roads, she said.

Several rescues in the county involved people caught by the flooded Mojave River, which usually flows underground and has a dry bed but had swollen to 17 feet high, Martinez said. Two homeless men stuck on an island in Victorville were airlifted to safety shortly before 8 a.m.

In Orange County, four hikers missing overnight in a flooded canyon in the Cleveland National Forest were rescued by helicopter Tuesday morning. The hikers’ car had been trapped on the far side of swollen Trabuco Creek. Rescuers used a bulldozer Monday night to retrieve five other people who became stranded by the creek.

Five more people were being escorted from cabins deep in Trabuco Canyon, said Capt. Greg McKeown with the Orange County Fire Authority. They were not injured but chose to leave because of worsening conditions, he said.

"This water is rising fast, it’s moving fast. Just don’t try to drive through it, you just don’t know how deep it is," McKeown said. "Rising water can move fast, it can move a car, it can move people."

Sheriff’s deputes were patrolling canyon areas scorched by fire in 2007 and remain at risk for mudslides, although no trouble had been reported, said sheriff’s spokesman Jim Amormino.

Southern California Edison reported 17,687 customers without power Tuesday. The hardest-hit areas included Lake Elsinore, San Bernardino and Claremont, spokeswoman Lois Pitter Bruce said. She urged patience as crews replaced downed wires and repaired flooded electrical vaults.

"This is very dangerous work," she said. "A lot of these equipment failures require going underground."

The storminess was being created by a cold, upper-level low off the Oregon coast that was steering a plume of moisture from the subtropical Pacific into California, the weather service said.

Unaccustomed to driving and dressing for so much rain, Southern California residents tried to go about their business — creeping along freeways, dodging puddles downtown and doing last-minute holiday shopping.

At a grocery store in La Canada Flintridge, Justin Buck trotted back and forth across the parking lot Monday night, collecting shopping carts in a clear plastic rain slicker.

"I dreaded coming to work today," the 31-year-old said. "This coat isn’t keeping me dry either. The water runs off my back, down onto my legs and drips into my boots. It’s not that cold actually. You just get tired of being wet all the time."

While adults grumbled, children didn’t seem to mind the rain. Grade-schoolers in rubber boots splashed in the downspouts and preteens pretended to be too cool for rain gear.

"I love the rain because we get to stay in during gym class and watch movies. And at lunchtime, the kids run outside and come back all soaked and try to hug you," 12-year-old Amy Becerra said as she bounced up and down and giggled.

About 40 residents of the San Joaquin Valley farming community of McFarland were briefly evacuated early Monday due to threatened flooding.

Gary Farrell, general manager of the McFarland Parks and Recreation District, said Santa Fe Railroad crews kept Poso Creek free of debris so it wouldn’t overflow.

Resident Cristian Abundis, who lives on a street where water ran a foot deep, returned from an evacuation center and quickly started filling sand bags.

"We just want to be prepared," he said, dropping the bags around his doors and driveway.

Elsewhere, a small twin-engine airplane was reported missing on a 65-mile flight from Palm Springs to Chino. Federal Aviation Administration spokesman Ian Gregor said wreckage was found near Lake Perris but investigators won’t be certain that it’s the missing plane until they can get to the scene on Tuesday, if weather permits.

A nine-mile stretch of scenic Pacific Coast Highway in Ventura County, west of Malibu, remained closed because of saturated cliffs that unleashed a rock slide Sunday night.

"The geologist says it’s unstable, unsafe," said California Highway Patrol Officer Steve Reid.

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Associated Press writers Gillian Flaccus in Santa Ana, Terence Chea and Jason Dearen in San Francisco, Garance Burke in Fresno and Robert Jablon and Sue Manning in Los Angeles contributed to this report. Jeff Nachtigal reported for the AP from McFarland.