Persistent Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Possible
- Size
- 2–3
On northerly and easterly aspects, you can trigger a dangerous slab avalanche that breaks up to several feet thick on weak faceted snow that was buried last month. Slabs can be triggered remotely from below or adjacent slopes. Collapsing and cracking are clear signs of instability, although direct feedback on this problem has become less frequent. The distribution of this avalanche problem is highly variable from one steep slope to the next due to past avalanche activity. In some cases, the slope may have avalanched in late February and has yet to fill back in with enough snow to form a new slab. In other cases, the slope may have filled back in with a new slab or it has yet to release to begin with. Where the avalanche problem exists, you may be able to decrease your chance of triggering by avoiding trigger points and areas where the slab thins. When en doubt, head for lower consequence terrain or slope angles in the lower 30-degree range and less.
3/12: A large persistent slab that likely failed on Friday night from wind loading.