A "significant winter storm" will dump heavy snow and make travel dangerous as it makes its way across the West over the weekend, forecasters warned Saturday.
“High winds, heavy snow and heavy precipitation will reach the Pacific Northwest today, then impact California,” the National Weather Service said in a bulletin.
More than 5 feet of snow is expected in the Sierra Nevada, resulting in “extremely dangerous travel, especially across mountain passes,” it added.
The U.S. Forest Service activated a backcountry avalanche watch late Friday in the central Sierra, including Tahoe, and warned of higher avalanche danger Saturday into Sunday.
“Triggering avalanches would be easy on steep slopes in exposed and sheltered areas where new snow rests on top of weak snow or where wind-drifted snow exists near ridges,” it added.
Thirty inches of snow was recorded late Thursday night and overnight at Yosemite at the top of Mammoth Mountain ski resort near Mammoth Lakes, the most snow recorded so far in the region, according to The Associated Press.
Elsewhere 1 to 3 feet of snow are expected across mountain ranges of the West Coast, the weather service said.
In California, where drought is still ongoing, heavy rainfall and unsettled weather across the state last week has improved drainage basin conditions and soil quality, according to the national Drought Monitor.
The latest front hit the state capital hard Saturday, where more than 30,000 utility customers were without power at one point during the day, NBC affiliate KCRA of Sacramento reported. At the same time, downed power lines trapped five vehicles with people inside in Sacramento County, according to the station. They were awaiting rescue.
The traditional Pacific storm, produced in the churning atmosphere of the Gulf of Alaska, was sweeping south and east Saturday evening. A leading edge of rain was already appearing in San Luis Obispo and Santa Barbara counties and was expected to reach Los Angeles County in the evening, federal forecasters said.
National Weather Service lead forecaster David Gomberg said it was the second significant winter storm of the season, giving Californians some hope of ending the drought.
On Thursday, the National Climate Prediction Center said the La Niña weather pattern, which usually results in drier-than-normal winters for California, was expected to continue through the end of the year, with conditions after that could lay ground for a shift to a traditionally rain-soaked El Niño weather pattern.
Last year's winter held similar promise for rain and snow in California, but it didn't deliver. "Sometimes what happens is you’ll start off with a good run, but during La Niña winters January and February turn dry," Gomberg said.
The weekend's cold front could bring as much as 4 inches of rain to urban Southern California, from the U.S.-Mexico border to L.A.'s San Fernando Valley, forecasters said. "Excessive rainfall" and some flooding was possible, the weather service said.
The cold front is a return to winter tradition for Southern California, with 2 to 20 inches of snow expected in the San Bernardino and San Gabriel Mountains above 6,000 feet Sunday morning, forecasters said.
"Snow will also spread into the mountains of the Central Rockies and Arizona on Sunday and Sunday night, with totals of 6-12 inches, locally higher amounts, anticipated through early Monday morning," the National Weather Service said in a forecast statement Saturday.
The storm prompted NASA on Thursday to move its splashdown zone for the return of its moon-probing Orion capsule 300 nautical miles south of its original location off the coast of San Diego. The new zone is closer to Guadalupe Island, off the southernmost end of Baja California, Mexico.
Forecasters expected waves as high as 20 feet in open ocean west of San Clemente Island, which is just off the Southern California Bight, said San Diego-based National Weather Service meteorologist James Brotherton.
Mike Sarafin, Artemis I mission manager, said Thursday that the storm's unruly winds, waves and rain could be a challenge for recovery crews working in open seas — one reason the splashdown was moved.
"We moved south of the uncertainty zone," he said.
As the storm heads east, the National Weather Service said in a forecast statement that "confidence was unusually high for strong winds and significant snows to produce hazardous impacts" across the central and northern plains and into the Midwest starting Monday night.