Persistent Slabs
- Hochgebirge
- Waldgrenze
- Unterhalb der Waldgrenze
- Wahrscheinlichkeit
- Unlikely
- Größe
- 2–2.5
Slabs exist above widespread, weak layers (facets, surface hoar, crusts, and combinations). Persistent Slab avalanches are most likely in the thinner snowpacks of the Pioneer and Boulder Mtns in the southeastern part of this zone. Before triggering an avalanche, you're unlikely to experience obvious signs of instability like snowpack cracking and collapsing (or whumpfing). Persistent Slabs can release in surprising ways and break much wider than expected. You are most likely to trigger one of these avalanches where:
- The snowpack is relatively shallow - spots may exist where the wind frequently blows, and the slab is not uniformly thick
- Any part of the slope you are on or connected to is steeper than about 35 degrees
- The slope faces the northern 2/3 of the compass
- A smaller wind slab or loose snow avalanche overloads the buried weak layers
(2/26/2025) Large slab avalanche on Boulder Peak, Boulder Mountains. SE @ 10,000'. Photo: Sawtooth Avalanche Center