There are few places in the United States that receive more snow than the Sierra Nevada, and that’s exactly where a “potentially life-threatening” blizzard is regarding to strike. A doozy even by Sierra standards, the massive winter storm is set to drop 5 to 10 feet of snow, which will combine with winds over 60 mph to bring regarding whiteout conditions.
Blizzard warnings have been hoisted for much of the Sierra Nevada, including the Northeast Foothills, Motherlode and western Plumas and Lassen counties above 2,000 feet in elevation. They cover ski resorts such as Mammoth Mountain and Palisades Tahoe, and stretch as far north as an area near Redding, Calif. Farther north, winter storm warnings blanket the high terrain.
While not exactly the result of an atmospheric river, the days-long winter storm will be caused by persistent Pacific moisture steered ashore by a slow-moving upper-air disturbance. Moderate to heavy snow will fall between Thursday and Sunday, with the worst conditions slated for Friday night, when winds will be the strongest.
The National Weather Service office in Sacramento warned that the storm will bring a dangerous combination of very strong winds and heavy snow that might damage trees and cause extended power outages.
“Mountain travel will be extremely dangerous to impossible, especially Friday,” it wrote.
The Weather Service office in Reno, Nev., was even more stark. “Do not take this storm lightly,” it wrote.
“Whiteout conditions are very disorienting, so this is not the time to gamble with you or your family’s lives,” it said. It also warned of closed roads, air travel delays and cancellations, and an avalanche risk.
Coincidentally, the Sierra Nevada was under a blizzard warning exactly a year ago — but conditions are expected to be worse with this storm.
“This is a little different — it’s a lot heavier and a lot more snow,” Robert Baruffaldi, a senior meteorologist with the Weather Service in Sacramento, said in an interview. “If you’re living in the mountains, you might be snowed in for a week potentially. And if the power goes out, hopefully you have a lot of firewood.”
Unlike atmospheric rivers, which are dense plumes of robust tropical moisture that can stretch thousands of miles, this setup is comparatively tamer from a moisture standpoint for California (just a minor atmospheric river will hit the Pacific Northwest and very far Northern California). In fact, the amount of humidity contained in the air isn’t exceptional — that’s why flooding isn’t anticipated at lower elevations such as the Sacramento Valley.
Instead, it’s a persistent flow of moisture curling east around a zone of low pressure at high altitudes. The upper-level low will meander east from offshore of Vancouver Island and come ashore over southern British Columbia.
Around it, the jet stream will dive and slice east, acting as a conveyor belt to pump the moisture into the mountains. This conveyor belt is moving so quickly that the moisture is constantly replenished. (Picture the factory scene from “I Love Lucy” — even though there aren’t many
