Nearly 20 inches of snow could fall on the Sierra Nevada from Yosemite National Park to north of Lake Tahoe this week. Drivers could find blocked and buried mountain passes this Thanksgiving holiday, authorities warned.
A massive storm, reaching across about half of the state, is expected to move in Tuesday and peak Wednesday, where it will drop up to 18 inches of snow on mountain summits from Shasta County and Lake Tahoe to Yosemite, said Nathan Owen, a meteorologist with the National Weather Service in Sacramento.
Forecasters cautioned there could be whiteout conditions above 3,000-foot elevations and snow could fall at up to three inches an hour, dropping visibility to zero. People were warned to avoid driving through the Sierra Nevada between 11 a.m. and 5 p.m. Tuesday.
Up to a foot of snow will fall at elevations as low as 4,000 feet, which could jeopardize the Tioga Pass, Donner Pass and others cutting through the mountain range through at least Thursday, the weather service said. Though the storm will eventually pass, the cold is expected to remain, meaning so will much of the snow.
"I guess the ski resorts are pretty happy about it," Owen said. "But the biggest impact will be the travel across the Sierra Nevada."
The snowboarding and ski season kicked off across California a couple of weeks ago with the first big seasonal storm. The Tahoe resorts saw about 20 inches of snow while Mammoth Mountain received as much as 36 inches, tourism officials said.
In an indirect way, this storm and the one that preceded it two weeks ago are symptoms of the upcoming El Niño, experts say. Though these storms originated in the Gulf of Alaska, the fact they reached Northern California with so much snow indicates El Niño's water-warming influence has reduced the high pressure system that usually deflects them, said Bill Patzert, climatologist with NASA's Jet Propulsion Laboratory in La Cañada Flintridge.
"This is the earliest the ski resorts have been opened in many years.... They rarely open before Thanksgiving," he said.
The snow's effect on the state's drought is negligible this early in the year, experts say. Snowpack isn't calculated until January at the earliest and it's the powder that melts through the spring and feeds the state's reservoirs that will make the difference.
For up-to-date road conditions this week, call Caltrans at (800) 427-7623 or go to quickmap.dot.ca.gov.
Staff writers Rong-Gong Lin II and Rosanna Xia contributed to this report.
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