FILE - In an aerial view, structures are seen buried in snow on March 20, 2023, in Twin Bridges, Calif.
Justin Sullivan/Getty ImagesA powerful storm system is forecast to unleash a torrent of snow over the Sierra Nevada and the Tahoe Basin on Tuesday, bringing dangerous driving conditions and avalanche warnings in early spring.
Snow was falling over highways 80 and 50 on Tuesday morning, and chain control was in effect as of 11:15 a.m. Conditions are expected to worsen this afternoon, and the storm is forecast to bring "major" impacts, including road closures and reduced visibility, through Wednesday.
"It's not pretty out there. Actually, it's pretty nasty," Chelsea Peters, a forecaster with the weather service's Sacramento office, told SFGATE at 11 a.m. "Snowfall rates are expected to reach 3 to 4 inches an hour at the peak this afternoon, making for some nasty zero-visibility driving conditions. If anyone wants to drive to Tahoe, they should probably reschedule."
The heaviest snow is expected Tuesday, but snow showers are forecast to continue into Wednesday. A winter storm warning is in effect for the greater Lake Tahoe area, stating that "travel will be very difficult to impossible" through 5 a.m. Wednesday.
From Monday through Wednesday, the weather service predicts Lassen Volcanic National Park could pick up 60 to 80 inches; Donner, Carson and Ebbetts passes could see 36 to 48 inches; and Echo Pass is forecast to get 18 to 24 inches. (See more snowfall predictions from the National Weather Service's Sacramento office Twitter account.)
The system is expected to whip up strong winds in the Sierra Nevada, with isolated gusts over 80 mph possible over ridges.
With powerful winds and heavy snow in the forecast, the Sierra Avalanche Center warned avalanche danger will be high in the backcountry of the central and eastern Sierra Nevada and Mono County from Tuesday morning through Wednesday morning.
With "new snowfall and strong winds stressing" the snowpack, the center said avalanches are possible and they "may run long distances and can run into mature forests, valley floors or flat terrain."
Snow showers are expected to ease Wednesday night, and mostly dry weather is forecast for Thursday, offering an opportunity to drive to and from the mountains.
"Conditions really aren't going to improve until the event ends late tomorrow and into Thursday morning," Peters said. "Most of the day Friday should be pretty quiet, too. We have a weak weather system moving through over the weekend, but overall impacts shouldn't be as bad as Tuesday and Wednesday."