Extreme Avalanche Danger Reported in the Sierra
The backcountry in Northern California is currently facing a critical avalanche danger due to a lethal combination of high-intensity snowfall and gale-force winds.
Authorities are expecting natural avalanches as these hazardous conditions are set to intensify over today and into the night in the Sierra, according to the Sierra Avalanche Center. With an extreme avalanche danger warning in place for tonight during peak snowfall rates, outdoor enthusiasts are strongly advised against traveling in, near, or below avalanche-prone areas.
The gale-force winds have been particularly instrumental in forming dangerous wind slabs by drifting and depositing new snow. These wind slabs, primarily located above and near the treeline, are expected to grow larger and trigger natural avalanches more readily as the storm escalates. There’s a significant risk that avalanches starting above could sweep down into forested and low-angled areas at the bottom of drainages and valley floors, making even seemingly safe areas perilous.
Adding to the avalanche risk are storm slabs that have developed atop a fragile layer of old snow. These weak layers could lead to avalanches that are both widespread and easily triggered, even on slopes that barely meet the avalanche terrain threshold, around 30 degrees.
Given these conditions, even non-avalanche terrain below 30 degrees is not entirely safe today, especially if there’s steeper terrain connected above or adjacent that could facilitate remote triggering. Avalanches may also run into or through areas with trees.
