Avalanche Threat, Thundersnow; Atmospheric River To Bury Sierra Under Several Feet Of Snow

SAN FRANCISCO (CBS SF) -- An atmospheric river bearing down on Northern California from the Gulf of Alaska Saturday will bring much needed rain for the parched hills and reservoirs of the Bay Area, but it's most potent punch will be in the Sierra where forecasters were warning of several feet of new snow.

A winter storm warning has been issued for the Tahoe area from 10 p.m. Saturday to 10 p.m. Tuesday.

"Travel in the Sierra is expected to be extremely slow if not impossible at times due to heavy snow beginning Sunday for those areas near and north of US-50, spreading south with all Sierra travel affected by Monday," National Weather Service forecasters on Reno posted Saturday. "Peak intensity snow rates could reach 1-3 inches an hour from Sunday night through Tuesday."

By the time the blizzard conditions move eastward, forecasters said more than 6 feet of snow could fall along the Sierra Crest and more than 3 feet at Lake Tahoe.

There is a threat of avalanche conditions and even a rare thundersnow event.

"This one (thundersnow) is definitely on the table Monday night into Tuesday morning with unstable air from the low moving inland," forecasters said. "If this does occur, localized heavier snowfall rates and/or lowering of snow levels is possible."

High winds will also roar through the region.

"Sierra ridges are expected to see winds gusting over 100 mph at times leading to near white-out conditions along with the snow," forecasters said.

And there will only be a brief respite for the snows return.

"While the storm will begin to wind down by Tuesday evening, digging out after the storm may keep travel impacted into Wednesday," forecasters said. "Then, there is another winter storm following right on its heels midday Wednesday into Thursday night."

A week of snow is just what the resorts and businesses in the region need after a dry November left only a few ski runs open and slowed the normal weekend crush of visitors.

Sharon King who runs Uncorked -- a wine shop in downtown Truckee -- is hoping the snowy blast will eventually boost business.

"It's all just so weather dependent here and tourist dependent and COVID dependent," she said. "It's been a wild ride. I've missed the happy faces and the travelers."