SAN FRANCISCO — A powerful winter storm unleashed heavy rain and strong winds across Northern California on Wednesday, triggering evacuations and power outages, and heightening fears of widespread flooding and debris flows.
Pounding rain and winds battered the Bay Area and surrounding regions Wednesday evening, prompting scattered evacuations.
The moisture-rich atmospheric river — fed by a plume of subtropical water vapor at the lower and middle levels of the atmosphere — is expected to bring wind gusts up to 60 mph and more than 6 inches of rain in some parts of the Bay Area through Thursday. The Sacramento Valley can expect up to 4 inches of rain and some areas in the foothills could see up to 6 inches.
Wednesday’s storm is the third atmospheric river that’s hit California in the last two weeks. The successive storms have brought a deluge of water to the drought-stricken state, prompting Gov. Newsom to declare a state of emergency to “support response and recovery efforts.”
The weather service is warning of rapid rises in creeks, streams and rivers across the region, as well as gusty winds that will likely bring trees and branches down, causing “localized damming of waterways.”
The heaviest bands of rain are expected to hit the central San Francisco Bay Area between 5 p.m. and 8 p.m. local time, areas of the inland East Bay between 8 p.m. and 10 p.m., and the Central Valley after 10 p.m. Rain rates of up to 1 inch per hour are possible, according to the weather service.
Flash flood watches have also been issued in several burn areas, including the area of the August Complex fire, the River Complex fire, the Mosquito fire and the western region of the Dixie fire. A flood warning is in place for the Russian River near Guerneville in Sonoma County, which officials say could see moderate flooding Thursday.
“The strong winds we’re expecting today on already-saturated soils and additional rainfall expected in the next 24 to 48 hours are really going to exacerbate the flooding concerns and the potential for wind damage and downed trees,” said Roger Gass, a meteorologist with the Bay Area National Weather Service.
Even without heavy rainfall, the Highway 1 underpass at Highway 101 in Mill Valley was already flooded by mid-morning. Strong winds caused delays and more than 70 incoming and outgoing flight cancellations at San Francisco International Airport Wednesday afternoon.
A portion of the city of Watsonville in Santa Cruz County was ordered to evacuate Tuesday night. With the incoming rain, authorities became concerned that a culvert under a major street that was damaged in a previous storm could fail making the roadway impassable for medical and law enforcement resources, according to the Santa Cruz County Sheriff’s Office.
Santa Cruz County has already suffered $10 million in damage from recent storms. The sheriff’s office also issued evacuation warnings in the northern rural areas of the county, which was burned by the CZU Lightning Complex fire in 2020, one of the most destructive fires in state history.
Rural southern coastal areas of San Mateo County are also under an evacuation advisory. The area is at risk of mudflows and landslides, authorities say.
In San Jose, officials were working to evacuate unhoused people staying near creeks. A similar effort was underway in Sacramento where officials were trying to convince unhoused people living along the American River to relocate to safer ground in advance of the storm.
But as clouds gathered Wednesday afternoon, marking an end to the brief respite between deluges of rain, some said they had no plans to do so.
Mark, who declined to give his last name, said he had spent several days trying to weatherize his camp so it would make it through the storm. The 58-year-old had erected it right next to a levee adjacent to the American River near downtown.
“It’ll hold up,” he predicted, adding that he wasn’t worried about rising water in the river because he believed he was high enough to avoid inundation.
On Wednesday morning, Land Park, near the state Capitol, was filled with the sound of wood chippers as crews worked to remove trees damaged by the last storm, some of which leaned at precarious angles with their roots exposed. Dozens of trees were toppled in recent days, and more are expected to fall during the evening, when winds are anticipated to become more severe.
San Francisco Mayor London Breed said the city was “preparing for a war” as officials passed out sandbags and residents braced for another several days of rain. The San Francisco Bay Ferry suspended service Wednesday on lines serving South San Francisco and Harbor Bay in Alameda, citing strong winds in the forecast.
Several businesses across the Bay Area, including Apple Stores and the East Bay SPCA animal shelters in Oakland and Dublin, closed early ahead of the storm.
Thousands of Pacific Gas & Electric customers lost power Wednesday, and the utility has deployed additional crews to deal with outages.
Wednesday’s so-called Pineapple Express storm comes on the heels of a New Year’s Eve system that dumped more than 5 inches of rain in San Francisco. It was the area’s second wettest day in more than 170 years of records, officials said.
At least three people were killed during the earlier storms, according to officials and local news reports. One was a 72-year-old who was struck by a falling tree in Santa Cruz. The bodies of two others were found near where the Cosumnes River flooded in Sacramento County, inundating Highway 99.
The series of atmospheric rivers that started toward the end of December was somewhat surprising after one of California’s driest years on record, which left reservoirs drained and soils parched.
“California is an extraordinary state and we experience extraordinary weather,” Wade Crowfoot, the secretary of the California Natural Resources Agency, said during a news conference Wednesday. “At the same time, we know that climate change is supercharging this extreme weather.”
Crowfoot noted that despite the heavy snowfall and rain, the state remains in the third year of an intense drought. It has marked the driest three-year period in the state’s history, he said.
“We’re still in the first half of the game. We’ve got major points on the board in terms of precipitation, snow and rain,” he said. “That will be helpful in coming dry months, but we’re a long way from understanding how this wet season impacts our overall drought.”
Experts say while the system is expected to bring heavy rain, it’s not simply the strength of this storm on it’s own that has prompted damage concerns, but instead the culmination of all the recent storms.
In October 2021, a similarly strong atmospheric river brought significant rainfall to the state but did not cause nearly the same amount of damage because the conditions leading up to it were more dry, said Daniel Swain, a climate scientist at UCLA.
Now, “it’s going to take a much lesser storm to produce much greater impacts given how wet it is,” he added.
Karla Nemeth, director of the California Department of Water Resources, said the latest series of storms is the most powerful set since 2017. Storms that year nearly caused the failure of a retaining wall in California’s second largest reservoir, Lake Oroville, and brought an end to California’s prior long lasting drought emergency.
“The most vulnerable places in California right now are rural levees — they are not required to meet the same standards as the levees that protect our our more urban communities,” Nemeth said.
