Heavy rains pound Southern California, forcing evacuations

An unusually strong storm system that was linked to at least two deaths lashed Southern California with heavy rain Saturday, bringing a risk for flash flooding and landslides and forcing evacuations in areas of Los Angeles County recently burned by wildfires.

The region has been wet since Thursday night, but the heaviest rain fell Saturday as the storm stalled over the region, drawing moisture off the Pacific Ocean.

As of early Saturday afternoon, there were no reports of major landslides and the rain over Los Angeles County was easing. Flood warnings in the area expired at 2 p.m., and county officials planned to lift all evacuation warnings and orders by 6 p.m. Debris flow was no longer anticipated in burn areas.

The main front of the storm had passed through the county, but forecasters warned that there was still a chance of thunderstorms through the night.

The system was continuing to dump rain in coastal areas between Orange and San Diego counties and was spreading inland into southeastern California and southern Nevada.

The storm pulled in a band of moisture known as an atmospheric river, bringing rain to Santa Barbara and Ventura counties overnight and spreading into Los Angeles County by Saturday morning.

By early Saturday afternoon, some locations in the mountains of Santa Barbara County had recorded more than 8 inches since Thursday. Downtown Santa Barbara had received more than 4 inches.

As of noon, downtown Los Angeles had recorded nearly 2 inches of rain since Friday – more than double the average monthly total of 0.78 inches for November.

The storm system moving through the region and a second system arriving on its heels in Northern California on Sunday have churned up seas and brought big waves to beaches.

At Garrapata State Beach along the Big Sur coastline, a father and his 5-year-old daughter were swept out Friday by waves estimated to be between 15 to 20 feet high. The Monterey County Sheriff’s Office confirmed that the father was later found dead and said that the child was missing.

And a 71-year-old man in Sutter County, near Sacramento, died after his vehicle was swept away by floodwaters, according to Sierra Pedley, a spokesperson with the Sutter County Sheriff’s Office.

Todd Hall, a forecaster with the National Weather Service, said that the rate at which the rain was falling Saturday was impressive. The burn scar from the Palisades fire received half an inch of rain in 15 minutes Saturday morning, a rate at which a debris flow could occur.

Burn scars are susceptible to debris flows from heavy rain because wildfire flames have destroyed the vegetation and cooked the soil. The debris flows start when a flood picks up sediment as it moves quickly across a hardened landscape, without any vegetation to stop it.

Some Los Angeles County residents, including those in areas that were burned during the Palisades and Eaton fires in January, were under evacuation warnings until Saturday evening. (A warning means that people should be prepared to leave quickly, while an order means it is time to leave.)

Some parts of Ventura County were also under evacuation warnings, including in the area burned by the Mountain fire late last year.

By Saturday morning, the weather service said there were reports of minor flooding on roadways across the region. Rocks had fallen onto some canyon roads.

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The coastal mountains of Southern California, from the Santa Monica Mountains to the San Bernardino Mountains, are perfectly oriented to wring the moisture out of the atmospheric river and produce heavy rain.

“The moisture will hit those mountains dead on,” said Park Williams, a climate scientist at UCLA. “Those mountains act as a wall, and the water slides down the mountains and then it goes into the city.”

In one chain of events, the heavy rain pouring down the mountains and into the urban areas can cause traffic delays on roads, scattered flash flooding, and minor mudslides and debris flows.

This article originally appeared in The New York Times.