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Cold storm dumps snow on Southern California mountains, threatens severe thunderstorms

AREA/CITY: San Bernardino Mountains The chain control check point on highway 18 when it was set up at Arrowhead Villa RD. It has since in the last 20 minutes been moved all the down to The Crestline Bridge with R2 restrictions being enforced. The San Bernardino Mountains are getting hammered by a snow storm by what was originally forecasted to be a very light and low producting weather event. At around 7PM last night snow flurries started but with in an hour came heavy snow fall associated with heavy winds creating near white out conditions through out highway 18. The sudden blizzard like conditions caused numerous drivers to get stuck in various places forcing them to put on chains in the middle of the highway or just getting plain stuck.
Workers check vehicles for snow chains at California 18 and Arrowhead Villa Road in Lake Arrowhead on Friday. (OnScene.TV)

The strong, cold storm that blasted damaging Santa Ana winds across the Southland on Thursday changed course overnight, dumping up to a foot of snow on San Bernardino County's highest peaks and threatening thunderstorms throughout much of Southern California.

By early Friday, Snow Valley and Bear Mountain resorts had already received 12 and 13 inches of snow, respectively, and forecasters expect several more inches to fall by the end of the day.

“They could end up with 15, 16 inches of snow in some of the 7,500-foot elevations," said Alex Tardy, a National Weather Service meteorologist in San Diego. "It is significant, especially for March."

The storm was also threatening severe, albeit isolated, thunderstorms Friday afternoon and evening across Los Angeles and Ventura counties. Forecasters warned that such storms — whose timing and location are difficult to predict — could again bring high winds, hail and minor flooding.

A 20% to 30% chance for showers and thunderstorms would persist through Sunday, weather officials said.

Scattered showers were also expected through Saturday for inland areas of San Bernardino, Riverside, Orange and San Diego counties below the snow levels, with thunderstorms also possible.

But the storm's largest challenge Friday remained the heavy snow, which triggered school closures in some of the hardest-hit areas.

Rim of the World Unified School District canceled all classes Friday "due to high-elevation snow and hazardous road conditions," according to the district's website, and all but one school in Bear Valley Unified did the same.

Areas near Idyllwild got about 5 inches early Friday and even Mount Laguna in San Diego County recorded 3 inches, according to the latest counts. Elevations as low as 4,000 feet, including Garner Valley near Hemet and in Julian in San Diego County, saw about an inch of snow.

Read more: Santa Ana winds whip into Southern California, downing trees and knocking out power

As snow continued to fall Friday afternoon, Tardy said another 1 to 5 inches would be likely, with higher amounts at higher elevations. Most of the snowfall is expected through Friday evening, but he said some could stick around Saturday.

“We’ve seen the coldest and worst part to the storm,” Tardy said Friday morning. He said the heaviest snowfall began about 9 p.m. Thursday through 4 a.m., when 1 to 2 inches fell per hour on Big Bear and other places.

A winter storm warning remains in effect for the San Bernardino and Riverside county mountains above 5,500 feet through 6 p.m., warning of heavy snow and winds gusting up to 45 mph.

Read more: California ski resorts look to the latest storm for snow to help kick off the season

“The storm that brought the wind yesterday moved right over Southern California," Tardy said. Because it came in from the east — as opposed to off the Pacific, like many systems that hit the Southland — it was initially dry and cold — bringing strong winds without precipitation.

“Once the storm settled over the area, it wrapped up moisture from the south and brought it back into the area," Tardy said, thus the snow.

The worst of the strong winds have subsided, but much of Los Angeles County remained under a wind advisory until 11 a.m. Friday with some lingering offshore flow, Tardy said. Gusts Friday were expected to reach up to 45 or 50 mph in some of the region's windiest corridors, including the Santa Monica Mountains, the San Gabriel Mountains and along the Grapevine — but that's still much lower than Thursday's highest gusts. The top speeds hit 86 mph at Magic Mountain Truck Trail east of Santa Clarita and 87 at Marshall Peak near Crestline, according to the National Weather Service.

Damaging winds also remained a concern across the southern Sierra, with a high wind warning in effect through 5 p.m. for Kings Canyon, Sequoia and Yosemite national parks, and along the upper San Joaquin River.

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This story originally appeared in Los Angeles Times.