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The central part of the state was expected to bear the brunt of the winter storm, which has prompted a state of emergency in dozens of counties.
Judson JonesDerrick Bryson TaylorMichael LevensonLivia Albeck-Ripka and
Judson Jones is a meteorologist and reporter for The Times.

A dangerous winter storm was dumping heavy precipitation over large swaths of California on Friday, raising the risk of significant flooding and pushing cities to issue evacuation warnings.
The storm, known as an atmospheric river, began on Thursday and was forecast to bring heavy rain and snow over parts of the state through the weekend. Central California was expected to be hit the hardest, and considerable flooding impacts were possible across portions of the central coast and the San Joaquin Valley, forecasters said.
As of Friday morning, most of California’s more than 39 million residents were under a weather warning or advisory, and dozens of counties were under a state of emergency. The number of power outages was also rising.
Use these maps to follow the storm’s forecast and impact.
Forecasters have warned of “copious amounts of heavy snow” in the mountains of Northern and Central California through Friday, some of it in mountain towns already buried in snow from weeks of storms.
Excessive rain was also forecast along the Central Coast, and forecasters warned that significant snowmelt at lower elevations could trigger flooding — all before another atmospheric river approaches next week.
Even by the standards of a state that has faced a brutal few weeks of extreme weather, the impact could be severe.
“This is an unrivaled, unparalleled weather event not experienced in several decades, perhaps back to 1969,” Kris Mattarochia, a science and operations officer at the National Weather Service office in Hanford, Calif., said at a news conference.
Gov. Gavin Newsom expanded on Thursday a state of emergency that he had declared last week for 13 counties to include 21 more, many of them in Northern and Central California. The California Department of Transportation had more than 4,000 employees working statewide, including more than 57 who were operating snowplows, graders, loaders and dump trucks in San Bernardino County.
The California National Guard was moving high-water vehicles into position in preparation for flood-response operations, and San Francisco said that it was giving away 10 sandbags per address to residents and businesses.
It didn’t take long for the storm to start dumping rain and snow, causing municipalities across the state to race to respond.
The city of Merced, about 115 miles southeast of Sacramento, issued an evacuation warning for some residents living around Bear Creek. San Jose issued evacuation orders to homeless residents living along the county’s rivers and creeks. Monterey County began urging some residents to prepare to evacuate.
The storm posed clear risks to road safety. The fire department in Contra Costa County, east of San Francisco, said on Twitter that one person was in critical condition after a four-vehicle accident that the authorities believed was linked to the weather.
South of San Francisco, a 40-mile coastal stretch of California’s iconic Highway 1 was closed in the counties of Monterey and San Luis Obispo after reports of rockfalls. The California Department of Transportation reported spinouts and emergency work on other roads.
Statewide, about 70,000 customers were without power as of Friday morning, according to Most of them were in Monterey County.
Livestock was at risk in some places, too. In Northern California, the authorities were working with state and federal agencies on Thursday to drop hay for stranded cattle in the hill country of Humboldt County.
“We know that there have been some cattle that have died,” said William Honsal, the county sheriff. “We will not know the number until the snow melts.”
At higher elevations, the storm arrived as mountain communities continued to dig out from blizzards that occurred last month. At least 13 people have died in the snow-packed San Bernardino County region since Feb. 23, although only one of the deaths was immediately connected to the winter weather, officials said.
The latest storm could bring up to two feet of snow in the Coastal Range and Shasta County Mountains and up to eight feet in the Sierra Nevada, the Weather Service said.
Rain and flooding, though, are the main concerns.
Significant river swelling was expected into the weekend in many parts of Northern and Central California because of rainwater runoff and reservoir releases, the California Nevada River Forecast Center said.
The Santa Lucia Mountains in coastal Central California could be inundated with up to 15 inches of rain, flooding roads and creeks, and producing mudslides. In the Bay Area, one to four inches of rain was expected at lower elevations and as much as 10 inches at higher elevations through Friday.
Along the Central Coast, the stretch from Salinas to San Luis Obispo, as well as the inland regions surrounding Fresno and Visalia, will be at “high risk” on Friday, the Weather Service said on Twitter. The last time this category was used in the region was in 2010.
The storm was also forecast to bring heavy rain to communities above about 9,000 feet, where there are large amounts of snow. Deep snow could absorb the additional moisture at such elevations, but that doesn’t mean the rain isn’t dangerous. It could add weight to the snow, putting additional stress on buildings and increasing the risk of avalanches.
Another risk is that significant snowmelt could worsen the flooding risk in areas with shallow snowpack, typically below 5,000 feet, such as creeks and streams in the foothills of the Sierra Nevada.
“Any sort of travel is discouraged, especially up in the mountains,” said Katrina Hand, a meteorologist at the Weather Service office in Sacramento.
Judson Jones is a meteorologist and reporter for The Times, covering the most extreme storms across the globe. More about Judson Jones
Derrick Bryson Taylor is a general assignment reporter. He previously worked at The New York Post’s and Essence magazine. More about Derrick Bryson Taylor
Michael Levenson joined The Times in December 2019. He was previously a reporter at The Boston Globe, where he covered local, state and national politics and news. More about Michael Levenson
Livia Albeck-Ripka is a reporter for The Times based in California. She was previously a reporter in the Australia bureau. More about Livia Albeck-Ripka
Mike Ives is a general assignment reporter. More about Mike Ives