Heavy rain headed to Southern California with mudslides possible in burn areas

The 5 Freeway in Castiac, closed Wednesday due to poor weather  at higher elevations
An empty stretch of Interstate 5 through Gorman on Wednesday as a series of winter storms rolls through California.
(Myung J. Chun / Los Angeles Times)

A winter storm barreling toward Southern California threatens heavy rainfall that could trigger mudslides and debris flows in vulnerable areas.

In anticipation of the rainfall, the National Weather Service issued a flash-flood watch in the areas burned in the Bobcat, Lake and Ranch2 wildfires last year. Without vegetation to hold it in place, the soil is weak and at heightened risk for debris flows and mudslides, experts warn.

The Grapevine area of the 5 Freeway reopened in both directions about noon Wednesday as the storm drenched the Central Coast and residents of fire-scarred areas braced for mudslides.

Motorists navigating the high-elevation pass are being escorted by the California Highway Patrol. The freeway had been closed for several hours because of snow.

The Los Angeles area remained dry Wednesday morning, but a few showers could arrive late in the day, with heavy rain expected through Friday afternoon, according to the National Weather Service.

A winter storm swept over much of Southern California, dusting mountaintops with snow and bringing traffic to a standstill on several passes.

Jan. 29, 2021


From 1.5 to 3.5 inches of rain are expected on the coast and in the valleys, with 2 to 5 inches in the foothills. Mountain areas above 6,000 feet could see 1 to 3 feet of snow.

There is a “good possibility of moderate debris flows” in areas burned by the Bobcat fire, said Joe Sirard, a meteorologist for the National Weather Service in Oxnard, who also warned of flash floods from heavy downpours.

Urban and street flooding is also likely as the rain picks up.

“With enough high-intensity rainfall, there could be a flash flooding even away from burn areas,” Sirard said.

In San Luis Obispo, 1.5 to 2 inches of rain had fallen by early Wednesday morning. “Copious amounts of rain” are expected in the foothills, the weather service said, and a flash flood watch is in effect until Thursday evening.

“Significant” mud and debris flows could affect Highway 101 and the burn scar left by the Avila Beach fire last summer, forecasters said.

In the Santa Cruz Mountains, some residents have evacuated, while others bought supplies and hunkered down amid warnings that the storm could trigger massive debris flows, road closures and prolonged power outages in areas scorched by the CZU August Lightning Complex fire.

Santa Barbara County is expected to see steady rain, totaling 3 to 6 inches. Meteorologists project wind gusts of 30 to 50 mph in all areas and more than 65 mph in northern mountain areas. Snow levels are expected to drop from 6,000 to 4,500 feet by Thursday night.


The atmospheric river that was traveling south is stalled in coastal California, threatening mudslides and debris flow in areas previously burned by wildfires.

But the forecast for Southern California is largely unchanged, said Lisa Phillips, a meteorologist at the National Weather Service in Oxnard.

“The storm is briefly moving up the coast but it’s still expected to push through Southern California,” Phillips said.