California Storm: At Least 17 Dead As Flash Floods and Mudslides Hit

At least 17 people have died in California's barrage of winter storms—a rise of three since Monday, Governor Gavin Newsom said while visiting storm-damaged businesses in Capitola, on the Santa Cruz coast, on Tuesday.

"We now have 17 confirmed—and I underscore 'confirmed' tragically, just confirmed—dead," he told a press conference. "Two more related to lightning strikes and a vehicle accident in the Tulare County area."

Noting that at least three more highly-charged storms were anticipated to head California's way until at least January 18, Newsom added: "That number, tragically [...] is likely to grow."

The latest deaths include a pickup truck driver and a motorcyclist—who died Tuesday morning when a tree fell on them on Highway 99 in the San Joaquin Valley—reported the Associated Press, citing the California Highway Patrol (CHP).

As the West Coast has been battered by a series of atmospheric river storms since late December, California has been deluged with rainwater – between 400 and 600 percent of historic averages, the National Weather Service said on Tuesday – which has led to flooding, rock and mudslides that have been exacerbated by the drought conditions the state has been suffering.

Flood warnings remain in place for swaths of the state still reeling from Tuesday's weather front, and flash flood warnings were in place for Los Angeles County, San Francisco and the Bay Area, and San Joaquin Valley.

Around 48,000 Californians are under evacuation orders, and just under 48,000 further residents are under evacuation warnings, Wade Crowfoot, California's natural resources secretary, said at the same press conference. Newsom stressed that the number "is dynamic and it will change."

While high winds toppling trees and power lines have already proven deadly, California's soil is now highly saturated with water, causing mud and rock slides across the state.

Video footage, recorded by a CHP Fresno officer on Route 168 near Shaver Lake, to the northeast of Fresno, shows a massive rock slide from a nearby hillside onto the road. CHP later credited Officer Jones "who was within 200 feet of the huge rockslide yesterday but still managed to keep the camera and his nerves still."

In Santa Barbara County, approximately 400 people were cut off from leaving the Rancho Oso camp ground due to a mud and rock slide across the road, the local fire department said. Emergency responders were able to clear the section of the road and those trapped were able to leave.

In Orcutt, a town immediately south of Santa Maria, a section of road, sidewalk and front yards had been washed away after the ground underneath gave way to floodwater, images from the scene produced by the Santa Barbara Fire Department show.

According to The Hollywood Reporter, Mulholland Drive, a famous route in western Los Angeles, was subject to a mudslide on January 9.

Christopher Kilburn, professor of geophysical hazards at University College London, U.K. told Newsweek: "As the ground soaks up more and more water, two things happen: first of all, the ground gets heavier as it's full of water, which it wasn't before. And secondly, as you increase the amount of water inside the soil or rock, you can build up the water pressure in that rock, and that tends to push adjacent bits of rock apart."

California remains in drought despite the recent weather events, and during the long, dry periods of 2022, the soil has become less permeable. As such, the sudden onslaught of so much precipitation in a short space of time is running off the ground more than it typically would, leading to more intense flooding and mudslides.

"Any gardener who has forgotten to water their flower patch during a heatwave has first-hand experience of this," Dan Shugar, a geoscientist at the University of Calgary, told The New York Times.

Kilburn said that the wildfires California has experienced "has a cumulatively destabilizing effect as it removes the vegetation and it removes the roots. The vegetation often binds soil together and acts as a stabilizing factor. So if that's been removed, bit by bit, it means the structure today may be less stable than it was two or three years ago."

"We've had less people die in the last two years of major wildfires in California than have died since New Year's Day related to this weather," Newsom said. "These conditions are serious and they're deadly."

According to Jan Null, a meteorologist at Golden Gate Weather Services, December 26 to January 9 was the third-wettest 15-day period in San Francisco's history, with more than a foot of rain. The only times with more rain were two spells in the 1860s, he wrote on Twitter.

"We're soaked, this place is soaked. And now, [a] more modest amount of precipitation could add equal or greater impact in terms of the conditions on the ground," Newsom said.