Persistent Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Likely
- Size
- 2.5–3
New heavy snow and low-elevation rain will continue to pile weight on the buried persistent weak layers that exist across the forecast area. Before this new load, these layers showed signs of instability like whumpfing / collapsing and unstable results in snowpit tests. The added load of this storm will make triggering persistent slab avalanches likely. Failure of the persistent weak layers could produce very large and dangerous avalanches. In wind-loaded areas, they could be even deeper since more snow exists on top of these layers. People could trigger them remotely while traveling in lower-angle terrain near or below steeper terrain, and they could break wider than expected. These avalanches could happen anywhere in the forecast area. They may be more widespread and even easier to trigger in the Carson Range in the eastern part of the forecast area where the weakest snowpack exists.
Some uncertainty exists concerning how much snow will fall today and exactly when/where the persistent weak layers will break. Still, when they break, they will almost certainly produce large, dangerous avalanches. The uncertainty combined with the potential consequences and the difficulty associated with evaluating the persistent weak layers all leads to simple travel advice: avoid the problem by avoiding travel in, near, or below avalanche terrain today.
(1/15/2024)
Large natural avalanche between Lincoln and Anderson Peak-thought to have occurred on Sat Jan 13. See the size of the crown relative to the people. These kind of avalanches could occur today and will become more likely as more load piles up during the next few days.
