It’s been a week of howling wind and bitter cold in California as winter storms have dropped into the region from the far north. The cold air set the stage for snow at unusually low elevations late in the week. Now, it is combining with an atmospheric river to bring blizzard conditions and possibly unprecedented snowfall to Southern California.
The latest powerful storm, steered by a low-pressure system rotating off the California coast, is taking direct aim at the coastal mountain ranges that run between Santa Barbara and San Diego counties. An atmospheric river could linger over the region for more than 24 hours into Saturday, piling up feet of mountain snow while dousing lower elevations with flooding rains.
The region rarely experiences snow of this magnitude, which is more typical of the Sierra Nevada, according to Alex Tardy, the warning coordination meteorologist with the National Weather Service in San Diego.
“This is not Lake Tahoe, this is not Mammoth [Lakes], and we’re not talking about a month of snow,” he said. “We’re talking about a three-day storm putting 5 to 6 feet at a location like Big Bear.”
Tardy noted that for Big Bear Lake, a popular weekend ski destination about 100 miles east of Los Angeles, it is possible “that these three- to four-day totals will exceed anything that we’ve recorded before.” He also called the flood risk for urban and rural areas “significant,” given how much rain was expected to fall in a short period.
By late Friday night, the Weather Service in Los Angeles was warning of “life threatening flash flooding of creeks and streams, burn scars, urban areas, highways, streets and underpasses.”
Up to 7 inches of rain had fallen in some parts of Los Angeles County, with more on the way.
Treacherous blizzard conditions
An extremely rare blizzard warning is in effect until 4 p.m. Saturday for the mountains of Ventura, Los Angeles and San Bernardino counties.
It is the first such warning issued by the National Weather Service in San Diego since that office was established in 1997, and the first since 1989 by the Los Angeles office.
Although local mountain peaks can experience isolated blizzard-like conditions, the events are rarely this treacherous.
“For us to issue a blizzard warning, meaning that conditions for the area are so bad that you need a warning — that just hasn’t happened before,” Tardy said.
Widespread heavy snow of 2 to 5 feet is forecast, with up to 8 feet possible at the highest elevations. Winds gusting between 55 and 80 mph will create whiteout visibilities.
“There will be very dangerous conditions in our local mountains — we can’t emphasize that enough,” Joe Sirard, a meteorologist with the National Weather Service in Los Angeles, said in an interview. “People don’t want to be on the roads in the mountains with this storm; you just have to hunker down and ride out the storm.”
Those dangers include a chance of avalanches in the area because of the combination of the heavy snow load and steep terrain.
Low-elevation snow
With the coldest storm of the season, much of California saw snow at unusually low elevations — between 500 and 2,000 feet, and in some cases lower — overnight on Thursday and into Friday.
It coated the peaks above wine country, the San Francisco Bay Area, and the plunging coastline of Big Sur.
There were also heavy accumulations in locations that aren’t used to seeing as much, if any, snow, including Redding, the Napa Valley floor, and the Santa Cruz mountains, resulting in road closures and downed trees and power lines.
On Friday, the wintry weather closed Interstate 5, the main north-south corridor in California, at a mountain pass known as “the Grapevine,” north of Los Angeles.
The snow line is expected to drop again Saturday on the back end of the storm as it exits Southern California.
Sierra snowpack rising again
The Sierra Nevada is receiving a healthy dose of new snow this week, particularly in the southern half of the range.
The renewed storminess is welcome because the weather had turned quite dry since a succession of atmospheric rivers slammed the state in December and January. California will need additional rain and snow as the wet season draws to a close if it is going to continue to emerge from the drought — and not lose ground on the gains made so far this winter.
It's deep out there! We've received 26.2" (66.5 cm) of #snow over the last 24 hours, which brings our 3-day total to 45.1" (114.5 cm)!
We're expecting another 7-14" today before a break in the snow tomorrow and then plenty more starting Sunday!#CAwx #CAwater #Weather pic.twitter.com/DqIX85lTtY
— UC Berkeley Central Sierra Snow Lab (@UCB_CSSL) February 24, 2023
The Department of Water Resources warned this week that the northern Sierra, the key water catchment region for the state, could still end up with a below-average water year in 2023, because it has not received as much precipitation as areas farther south. However, with a cold, unsettled pattern forecast to continue into early March, additional storms should help to build the annual totals in the north.
“I would say there is going to be quite a bit of moisture coming in, with current models showing significant precipitation in California over the next seven to 14 days,” said Andrew Schwartz, the lead scientist at the Central Sierra Snow Lab at the University of California at Berkeley.
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February 25, 2023 at 09:30PM
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Unprecedented snowfall possible in California as wind and bitter cold continue - The Washington Post
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