Persistent Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Unlikely
- Size
- 1.5–2.5
Although instabilities are becoming increasingly harder to find, the most hazardous concern is the lingering threat of triggering a large slab that fails 2 to 4 feet deep on depth hoar, facets, and faceted crusts without obvious warning signs. In the Northwest Mountains, these slabs are most likely to be triggered in terrain where slabs are thinner or variable in depth from past wind events. The most reliable way to manage this problem is by choosing slope angles less than 30 degrees. Southerly aspects and elevations below ~10,500' offer safer snowpacks, where slabs are less common and weak layers are often capped by stronger crusts.
A large persistent slab ran naturally on the west side of Mt. Baldy on 1/10/2026.