As the rain fell in sheets on the fire-scarred mountainsides above La Canada Flintridge, Lynn Thompson barricaded her front door and windows with plywood and stashed her family photos at her daughter's house.

Like hundreds of foothill residents, Thompson packed her possessions and evacuated her home of 32 years, but not before her load of laundry dried.

"Sometimes you have to pay big bucks for these views, both emotionally and financially," she said.

The soil saturated by days of rain seemed to hold as a third powerful Pacific storm pounded California Thursday, but rain and snow shut down a major interstate, knocked out power to thousands and unleashed lightning strikes on two airliners on Wednesday.

Forecasters warned of yet another wave of rain and winds to come, with high surf battering the coastline and heavy snow in the mountains.

As Los Angeles Mayor Antonio Villaraigosa toured the Riverwood Ranch development in Tujunga to urge them to evacuate, cars were parked in driveways, horses were still in barns and smoke rose out of fireplaces.

Even though police officers and sheriff's deputies went door-to-door asking residents to leave, some refused to comply with evacuation orders in Los Angeles-area foothill communities below the steep San Gabriel Mountains where 250 square miles of forest burned in a summer wildfire.

Sheriff's deputies warned it might not be possible to rescue those who stay behind and asked them to fill out forms stating they'd been advised of the danger. Los Angeles officials reported only about 40 percent compliance by residents of 262 hillside homes in that jurisdiction.

Police Chief Charlie Beck sternly urged the rest to go, saying: "We're not doing this because your carpet is going to get wet; we're doing it because your life is at risk."

Henrik Hairapetian, 40, who builds custom 4-by-4 vehicles for a living, said he was undeterred because his Hummer H-1 would help him and his family escape the mud.

"I've driven through some hairy stuff and I'm sure we can get out if we need to," he said.

Hairapetian's neighbors all evacuated their homes, leaving him to guard their small cul-de-sac next to a burned hillside, where little tufts of grass were beginning to sprout where the summer's wildfire consumed the vegetation that would normally capture or slow runoff.

A few blocks up the street, public works crews checked Mullally Basin, which was gradually filling with mud and debris swept down from the hills.

Officials said the 28 flood-control debris basins protecting the area were near capacity but continue to function as designed.

The storms were testing months of preparations in burn-area neighborhoods from northeastern Los Angeles through La Crescenta, Glendale, La Canada Flintridge and Altadena.

Southern California has a history of fatal debris flows: 30 killed and 483 homes destroyed in 1934 in the Los Angeles-area foothills, and 16 killed in 2003 to the east in the San Bernardino Mountains.

In Northern California, 50 homes were ordered evacuated as a central coast river rose near Felton Grove in the Santa Cruz Mountains, but it receded later in the day.

The Grapevine stretch of Interstate 5 was closed for hours due to snow and ice in Tejon Pass north of Los Angeles.

Since the beginning of the week, more than 300,000 Southern California Edison customers had lost power.