LOS ANGELES – Southern California residents stacked sandbags yesterday ahead of possible flash flooding and mudslides in areas burned bare by recent wildfires.

Meanwhile, thousands in the Pacific Northwest remained without power or clean drinking water after a deadly wave of storms there.

In California, Orange County sheriff’s patrol cars broadcast warnings through loudspeakers urging about 2,000 people to get out of three canyons because some of the heaviest rainfall in more than a year was expected to hit the area overnight.

The evacuations could become mandatory later in the day as the storm approached, sheriff’s spokesman Jim Amormino said.

“It’s much better to do it early than wait for the slides to start,” he said. “The canyons are narrow; the roads are narrow. Sometimes if you wait too long, it’s potentially dangerous.”

In the Northwest, rescue and evacuation work ended as floodwaters continued to recede. Six people died in Washington, and another two died in Oregon. An elderly man was missing after he was believed to have fallen into a raging creek behind his house in rural Winlock, Wash.

About 640 people were still in shelters, 33,000 customers lacked power and about 18,900 had no safe drinking water, Gov. Chris Gregoire said. Fourteen water systems were shut down and people served by nine others were under orders to boil water. Some areas requested vaccines, especially for tetanus.

Helicopters took flood-stranded residents to safety at the height of the storm. By the time helicopter operations ended Wednesday evening, at least 300 people had been taken to safety in what Gregoire described as Washington state’s largest aerial search-and-rescue operation in a decade.

“Those folks who are literally homeless today still have a spirit in them,” the governor said. “They are determined to get back to their homes and get their lives back together again.”