Gov. Newsom puts most of California in emergency as atmospheric river storm arrives

With a strong atmospheric river storm bearing down on the state and creating flooding concerns following weeks of heavy snow, California Gov. Gavin Newsom on Wednesday evening expanded an emergency proclamation to 21 additional counties, with a majority of the state now covered.

The big storm is forecast to begin Thursday, bringing heavy rain and snow through the weekend, National Weather Service forecasts show.

The 21 counties added to the emergency proclamation are: Butte, El Dorado, Fresno, Humboldt, Imperial, Inyo, Lake, Mendocino, Merced, Monterey, Napa, Placer, Plumas, Sacramento, San Francisco, San Mateo, Santa Clara, Santa Cruz, Stanislaus, Tuolumne and Yuba.

Those join 13 counties for which Newsom declared an emergency last week: Amador, Kern, Los Angeles, Madera, Mariposa, Mono, Nevada, San Bernardino, San Luis Obispo, Santa Barbara, Sierra, Sonoma and Tulare.

The incoming system is warmer than the recent storms that have buried the Sierra Nevada mountains and wide swaths of the foothills with snow since late February.

Snow from Thursday through the weekend is expected to mostly stay above elevations of 4,000 feet, according to the weather service, with anywhere from 2 to 8 feet possible across parts of the Sierra Nevada.

At lower elevations, including the foothills and the Sacramento Valley, drenching rain is anticipated. Weather service forecasts show up to 3 inches possible in the valley between Thursday and Sunday morning, and as much as 6 inches falling in the foothills.

The heavy rain will create a potentially serious flooding risk. In the foothills, rain falling atop snow could produce substantial runoff from rain mixed with snowmelt, forecasters warned.

Rain could also cause collapses of roofs topped with heavy snow accumulations, according to the weather service and emergency officials.

All the while, strong wind gusts will develop Thursday afternoon and likely last through Friday afternoon, forecast to reach about 45 mph in the Sacramento area and foothills. Gusty conditions could lead to widespread power outages.

Isolated thunderstorms will also be possible Friday and Saturday across most of Northern California, according to the weather service, which could worsen flood conditions.

“The state is working around the clock with local partners to deploy life-saving equipment and first responders to communities across California,” Newsom said in a prepared statement. “With more dangerous storms on the horizon, we’ll continue to mobilize every available resource to protect Californians.”

Newsom said Caltrans, the California Highway Patrol, Cal Fire and other partner agencies are mobilizing to respond to snow- and flood-related emergencies, and that the Governor’s Office of Emergency Services has helped to open six shelters, located in San Bernardino, Stanislaus, Madera, Butte and Nevada counties.

Sacramento County proclaims local emergency for storms

Sacramento County also proclaimed a local state of emergency due to the winter storms.

The county in a Thursday news release warned of “significant transportation impacts, rising creek and river levels, downed trees, damage to infrastructure and localized flooding.”

The proclamation, which will be ratified by the Board of Supervisors during next Tuesday’s meeting, is the second issued by Sacramento County this winter.

The first came on New Year’s Eve, when a powerful atmospheric river storm led to intense, deadly flooding in southern portions of the county. Three people were found dead in or near vehicles, near Galt and Wilton, in the immediate aftermath of that storm; two others, both homeless, died in Sacramento County during January after trees fell on top of their tents amid gusty winds.

Other Northern California counties have declared their own local emergencies due to storm conditions. In Nevada County, Pacific Gas and Electric Co. as of Thursday morning reported 4,000 homes and businesses without power, roughly 1,500 of which have been in the dark for at least 10 days.

In the capital region, forecasts show Sacramento could get more than an inch of rain Thursday afternoon and evening, followed by three-quarters of an inch Friday. Rain will likely continue through the middle of next week.

The weather service has a winter storm warning in effect for the Sierra Nevada mountains, and a flood watch covering a majority of Northern California, each in place through 10 a.m. Sunday.