201912.29
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New Pacific storm Monday will again threaten SoCal mountain passes with snow

by in News

A Pacific storm was on course to bring rain and snow to Southern California late Sunday through Monday, threatening for the second time in less than a week to vex travel through the Tejon Pass between Los Angeles and Kern counties and the Cajon Pass from the Inland area to Las Vegas.

Winter weather advisories were set for mountains in Los Angeles, San Bernardino and Riverside counties, the National Weather Service said Sunday, with the Los Angeles advisory lasting from early Monday to 10 p.m. the same day, and the Inland advisory from early Monday to 4 a.m. Tuesday.

Weather is expected to be clear later Tuesday, with New Year’s Day expected to be dry with mild conditions, and even a warming trend later in the week, the NWS said.

But for Monday:

“Plan on slippery road conditions and reduced (visibility) due to blowing snow. Interstate 5 near the Grapevine and highways 2 and 39 will likely be impacted by accumulating snow and possible ice,” the NWS Los Angeles/Oxnard office warned Sunday. Snow levels will drop to 2,500 feet to 3,500 feet on Monday for that area with local wind gusts up to 60 mph for some mountain areas.

“Snow will likely accumulate on mountain highways, including the I-15 in the Cajon Pass area,” the NWS San Diego office said. Snow will fall as low as 3,500 feet in the Inland area, with heaviest amounts above 5,000 feet. Wind gusts were forecast to reach 35 to 50 mph in some Inland mountain passes Monday night.

Caltrans warned motorists bound for the Cajon Pass north of San Bernardino and Mountain Pass on the 15 Freeway near the Nevada border, “don’t travel during the storm,” and to expect delays and possible closures.

Rain was forecast to be light in the lower elevations, with the low-pressure system storm tracking away from the coast. Accumulation was expected to be a quarter-inch in Los Angeles County.

For Orange, Riverside and San Bernardino counties coast, valley and desert areas, the NWS forecast rain totals from a trace to around a tenth of an inch, with the coastal areas having the best chance for measureable rain.

The snow on the mountains is the result of “wrap-around moisture,” when precipitation falls along a comma configuration — in this case, over the ocean, then largely bypassing the interior valleys as it curves, and falling as snow in the Southern California mountains and passes.

The portion of the storm over the ocean did bring forecasts of high seas and surf, with a small craft advisory  issued for outer coastal waters from Santa Cruz Island to San Clemente Island from early Monday to  3 p.m. Tuesday.

Surf at Orange County beaches could reach 6-8 feet.

Select forecast highs and lows for Monday include: Los Angeles, 61 and 46 degrees; Long Beach 60 and 47; Anaheim 62 and 47; Riverside 57 and 44; and San Bernardino, 57 and 44.

The storm is not expected to be as strong as one that hit the area Thursday Dec. 26 and forced the shutdown of both the 5 Freeway through the Tejon Pass and the 15 Freeway in the Cajon Pass.