SAN FRANCISCO (CBS SF) — Showers lingered across the San Francisco Bay Area Tuesday, but the brunt of a potent atmospheric river roared into the Sierra, triggering blizzard conditions, hurricane-force winds and concerns over the threat of an avalanche.

Officials with the Sierra Avalanche Center were warning of possible slides in the Tahoe Area.

“We saw avalanches yesterday (Monday) that failed as wide as the terrain would allow, up to nearly 900′ wide across the Far East Ridge of Tamarack Peak in the Mount Rose zone,” the agency said on its website.

“These weak layers are a problem both above and below treeline and in both wind protected and wind drifted areas. Don’t mess around with this stuff right now. Avalanches could easily be larger than expected and occur in unexpected locations.”

The Eastern Sierra Avalanche Center in Mammoth Lakes also issued a warning for Inyo County and Mono counties.

“Heavy snowfall combined with strong winds and a weak underlying snowpack will likely create widespread areas of unstable snow,” the center warned. “Large human triggered and natural avalanches are likely.”

Meanwhile, the National Weather Service issued warnings and advisories as the snowfall rates increased in the Tahoe area early Tuesday.

“Palisades Tahoe received another 2 feet of snow overnight last night, bringing the storm total to more than 4 feet, with heavy snow still falling at the resort this morning,” the resort posted early Tuesday.

Kirkwood Mountain Resort was closed Monday, saying on social media that it was not safe to open with 17 inches of overnight snow and high winds. A California Highway Patrol car in Truckee nudged a big-rig up a snowy hill while smaller vehicles spun out, resulting in minor bumps and bruises but no real injuries, CHP Officer Carlos Perez said.

“It’s just so bad and so thick,” he said of the snowfall, with more expected Monday night. “We’re telling people that if they don’t need to be around this area, they probably shouldn’t travel.”

The Washoe County Sheriff posted early Tuesday that “Mount Rose Highway is currently closed from Douglas Fir to Fairview. Interstate 80 is currently closed over Donner Summit as well.”

Several feet of snow had fallen at the UC Berkeley Central Sierra Snow Lab.