GUERNEVILLE, Calif. (AP) – The strongest of this week’s drenching storms moved ashore Thursday in Northern California, raising the risk of flooding and mudslides in the region of already soggy hillsides and swollen rivers.

Flood and wind warnings were in place again north of San Francisco, where residents along the Russian River stacked sandbags to protect their properties.

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The river overtopped its banks in some areas and flooded streets Wednesday, but began to drop later in the day. The wine region community never dried out after damaging flooding during storms last month.

“They are saying this storm won’t be as bad as it was in January, but you never know, we’ll have to wait and see,” said Heidi Allen, a server at Trio Restaurant & Bar in Guerneville.

The National Weather Service warned that the nearby Napa River could swell beyond flood stage by Thursday evening and residents should be prepared to move to higher ground.

Southern California got a break from days of rain, but dense fog made for treacherous driving and led to flight delays at Los Angeles International Airport.

After days of steady rain, mudslides blocked a Santa Cruz highway in more than a dozen spots and slammed against a family compound, destroying one house and damaging another.

Jennifer Ray said a mudslide carrying rocks and trees knocked off her pregnant sister’s house from its foundation before dragging and overturning several of the family’s cars and damaging her own mobile home. Her family lives on a compound built on a Los Gatos hillside, where her father also has a home.

“All we could do is watch as it all came down and trap my mom’s dogs in her car,” Ray told KNTV. The dogs are now safe and no one was hurt.

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Nearly 5 inches of rain fell in a 12-hour span Wednesday in the San Joaquin Valley, swamping roads and swelling waterways to critical levels.

The water levels at an earthen dam on Lewis Forks south of Yosemite National Park that authorities said was in imminent danger of failing Tuesday had receded by Wednesday evening. But with more rain expected Thursday and Friday, things might get worse again, Madera County sheriff’s Cmdr. Bill Ward said.

Downstream residents in the rural Cedar Valley area should be ready to evacuate at a moment’s notice, he said.

To the north, officials shut down water flow from a dam in Butte County after chunks of concrete went flying off the emergency spillway, creating a 200-foot-long, 30-foot-deep hole.

The Department of Water Resources said the erosion at Lake Oroville does not pose a threat to the earthen dam or public safety, and the reservoir has plenty of capacity to handle the continuing rain.

Water officials released a test flow Wednesday afternoon to assess how much water could rush past the damaged spillway and planned another test Thursday.

The weather service said the storms were part of a “classic pineapple express,” referring to an atmospheric river phenomenon that carries moisture across the Pacific Ocean from Hawaii and dumps it on Northern California. It could deliver even more rain starting Thursday, forecasters predicted.

“If the model guidance is correct this next system could be even juicier moisture wise as it has a decent tropical connection,” according to a weather service statement.

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Copyright 2017 The Associated Press.