California on guard for mudslides

A storm hit parts of California with up to 175 millimetres of rain and spawned minor flooding, mudslides and road closures, but forecasters warn the real impact may be yet to come.

A storm walloped parts of California with up to 175 millimetres of rain and spawned minor flooding, mudslides and road closures Monday, but forecasters warn the bad weather's real impact may be yet to come.

A driver navigates a flooded stretch of the Great Highway in San Francisco on Sunday. Storms are dropping rain throughout California and blanketing the Sierra mountains with snow. ((Noah Berger/Associated Press))

More than 75 additional millimetres of rain expected across the region by Wednesday will hit already saturated hillsides, increasing the possibility of slides and flash floods, said Stuart Seto of the U.S. National Weather Service.

The relentless rains that pounded California through the weekend smashed rainfall records, caused numerous traffic accidents, downed trees and forced the cancellation of some horse races.

The weather service said rainfall accumulation could reach 500 millimetres in some isolated locations by Wednesday, when the first phase of the storm is expected to pass. After a brief respite, it is forecast to return late Christmas Day.

A 32-kilometre stretch of the scenic Pacific Coast Highway between Malibu and Oxnard was closed to commuters after a rock and mud slide Sunday night. The California Highway Patrol said no one was hurt.

Eastbound Highway 71 in Pomona was closed because of potholes and flooding, and a number of mountain roads were closed.

The system hit the state Friday after a large storm front moving out of the Gulf of Alaska met with subtropical, moist air coming across the Pacific Ocean.

Emergency declared

In Kern County, officials declared an emergency after two days of intense rain, a move that provides responders with faster access to country resources. The Bakersfield Californian reported that the rains left many neighbourhoods around the county dealing with high water. Some roads were closed and some homeowners stacked sandbags in hopes of staying dry.

The Los Angeles area, including downtown, Hollywood and the San Fernando Valley, received 75 to 100 millimetres of rainfall, while some northern mountain areas were hit with more than 175 millimetres.

Rainfall records weren't just broken, they were obliterated. The weather service said 86 millimetres of rain fell in Pasadena during three days. The old record was 37.5 millimetres in 1987.

The Santa Maria River briefly overran its banks Sunday and caused flooding in Guadelupe in Santa Barbara County, forcing an underdetermined number of people to leave their homes, fire officials said. The Santa Maria Times reported that the high waters began receding in the evening.

Flash-flood warnings were in effect for some areas, particularly mountain areas still scarred by recent wildfires, while flood warnings or flood advisories were issued for most of the region.

Residents of La Canada Flintridge were among those keeping a wary eye on the rain. More than 40 homes in the hillside city just north of Los Angeles were damaged or destroyed by a mudslide in February.

"We are holding up," said resident Lien Yang, who added he was warned to be prepared to evacuate. "It's coming down steady but not pouring. Therefore it doesn't cause a mud flow or flooding or anything like that. Hopefully, it's winding down and we'll have no threat this time."

One of his neighbors, Tom Smith, spent part of Sunday afternoon placing sandbags in front of his house.

Sierra Nevada ski resorts reported up to 45 centimetres of fresh snow Sunday. Forecasters said the area could get similar amounts every night until Saturday.