(CNN) - A strong storm system drenched some areas in California with snow and heavy rains as forecasters warned of mudslides and debris flows in areas ravaged by wildfires.
The system affected much of the state -- and especially soaked areas along the coast, according to the National Weather Service's storm prediction center.
"Southern California is particularly at risk for excessive rainfall and mudslides -- so a high risk has been issued for this region -- with a moderate risk stretching into Los Angeles," it said. The heavy rain and snowfall in the state will start easing Friday.
"Meanwhile, heavy snow will continue across the Sierra Nevada through the weekend -- where winter storm warnings will be in effect through Sunday."
In Northern California, homes tumbled down the hillsides as the downpour caused mudslides that swallowed up cars. Susan Gordon, who lives in Sausalito, said she woke up to the sound of rumbling when the mudslide hit Thursday.
She was asleep on the second floor when the mudslide lifted her home off its foundation, breaking it apart and pushing it down a hillside -- with her inside.
"It just happened too fast. I did not know what was going on," the 76-year-old said. "I was on the second floor. I heard something. I started looking for my phone."
Her duplex traveled about a block down the hill before slamming into another home and destroying both houses. She survived with scratches and bruises.
'Pineapple express' of rain and snow
California is at the center of what's known as a "pineapple express" that's bringing heavy rain, snow, wind and flooding to the West Coast this week.
More than 30 million people are under flood or flash flood watches from California to Arizona, including in San Francisco, Los Angeles and San Diego.
A pineapple express, also known as an atmospheric river, is a narrow corridor of concentrated moisture in the upper atmosphere. The series of storms originates in the Hawaiian Islands, pulls in a significant amount of moisture from the Pacific Ocean and takes aim at the West Coast.
Central areas of California have already been hit hard, receiving 3 to 8 inches of rain in a day in many places, according to CNN meteorologist Haley Brink.
The San Francisco area broke a daily record for rainfall Wednesday with 2.13 inches, Brink said.
Brink said the heavy rain and snow is tapering off in California.
"The risk for flooding and mudslides will continue only through Friday morning. Although the heavy snow in the Sierras will continue through the weekend," she said.
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