Massive waves slam California, with more expected Saturday

Waves as high as 25 feet continue to pummel the West Coast after a damaging barrage flooded beaches as far south as Los Angeles on Thursday and left logs scattered across roads as far north as southern Oregon.

Powerful cyclones over the North Pacific are combining with higher-than-normal tides to create dangerous waves and flooding.

The National Weather Service in Los Angeles called it “an exceptional high-surf and coastal flooding event that has not occurred in many years,” in a forecast discussion Friday.

Conditions improved somewhat on Friday, with the Weather Service downgrading high surf warnings to a lesser high surf advisory for much of the California coast.

Even so, authorities issued high-surf and coastal flood warnings until 2 p.m. Saturday for Northern California from the North Bay coast to the Big Sur coast, where breaking waves of 30 to 40 feet are still possible.

“Impacts will only slightly lessen into Friday before an additional strong wave front arrives from the northwest, reinforcing extremely dangerous conditions at the beaches again on Saturday,” the Los Angeles Weather Service wrote.

Already, emergency responders have had to rescue several people from the ocean in Southern California, according to Ariel Cohen, the meteorologist in charge at the Weather Service’s Los Angeles office.

“We are dealing with potentially deadly conditions at the beaches so we really just encourage everyone to stay away from the water and be prepared for coastal flooding,” Cohen said.

Warnings across coastal California

High surf warnings for waves of 15 to 20 feet, and up to 25 feet, are in effect through Saturday for beaches in Los Angeles, Ventura, Santa Barbara and San Luis Obispo counties. Waves of up to 15 feet are also forecast for San Diego and Orange counties through the weekend.

A coastal flood warning is in effect for beaches in Ventura, Santa Barbara and San Luis Obispo counties through 10 p.m. Saturday, while San Diego and Orange counties are under a coastal flood advisory - with less serious flooding expected - until 2 a.m. Monday.

Climate change could also be contributing to the higher seas. UCLA climate scientist Daniel Swain noted Thursday on X, formerly known as Twitter, that sea level rise is a background factor in the inundation seen in parts of California on Thursday. Higher sea surface heights right now, possibly due to the ongoing strong El Niño, may also be a partial cause, he said.

On Thursday, the giant waves arrived during mostly fair weather, but parts of the state will see rain Friday and into the weekend, exacerbating flooding.

“A lot of these places have smaller creeks and streams that run out to the ocean,” said Dalton Behringer, a meteorologist in the National Weather Service’s Bay Area Office. “But they’re not able to drain as quickly as they normally would if we didn’t have that coastal run-up.”

The storm system over the North Pacific will send a strong cold front into California that will bring heavy rain, thunderstorms and mountain snow to the northern half of the state on Friday. Rain totals will range from a half inch to nearly 5 inches for isolated spots of coastal mountain ranges. For the higher peaks of the Sierra, 12-18 inches of snow are forecast. Wet weather with a chance of thunderstorms will move into Southern California on Saturday, with a 30 percent chance of rain again on New Year’s Day in the Los Angeles area.

A warning for future flooding

Some of the worst-hit areas are in coastal communities that are still recovering from recent flooding events.

South of Santa Cruz, Capitola was heavily damaged by a bomb cyclone in January that wrecked the town’s wharf and closed some businesses for months. Waves once again rocked waterfront businesses on Thursday.

“Our message to those vulnerable communities is, you have to start planning the response and the changes now,” said Donne Brownsey, a previous chair of the California Coastal Commission.

Events with damaging waves may become more common in the future. Sea levels in California are expected to rise nearly 2 feet by 2050, according to the Coastal Commission. That is sure to exacerbate future flooding and storm surge. Average wave heights near San Francisco have risen since the 1930s, apparently due to climate change, according to an August paper from a researcher at the University of California at San Diego.

Coastal cities are starting to adapt to changing conditions by building costly sea walls, dredging sand to replenish vanishing beaches and, in some cases, paying vulnerable property owners to relocate.

“I think everybody knows you have a set of not great options,” Brownsey said. “You choose the best of bad options, but if you can plan for it, it gives you a lot more tools in the toolbox to address it.”