Persistent Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Possible
- Size
- 1.5–2.5
Weak snow that formed in November sits near the base of the snowpack in the majority of terrain above 8,500’. Loading from heavy snowfall and strong wind is stressing these weak layers, making them more likely to fail. Recent avalanches failing near the ground illustrate the nature of this problem. Avalanches in the upper portion of the snowpack also have the potential to step down to older weak layers and create very large avalanches. This is most likely to occur in very steep terrain that faces east through north. Wind loading will also increase the likelihood of this problem.
Two recent human triggered avalanches have been reported involving weak snow near the ground. Both occurred in steep, treed terrain that is sheltered from the wind. No signs of instability were observed prior to these avalanches.
(12/22/2025)
A snowmobile triggered avalanche that likely failed on weak snow from November.