Persistent Slabs
- Hochgebirge
- Waldgrenze
- Unterhalb der Waldgrenze
- Wahrscheinlichkeit
- Possible
- Größe
- 2–3
You could trigger 1.5-4 foot thick slabs, especially where wind formed drifts or stiffened the snow surface. Triggering an avalanche is less likely—but not out of the question—on steep slopes that are completely sheltered from the wind. The slabs rest above a variety of weak layers (facets, surface hoar, and crusts + facet combinations). The widespread nature of these weak layers means avalanches are possible on many aspects.
Snowpack cracking and collapsing or whumpfing are clear signs of unstable conditions. However, a lack of these obvious warning signs doesn't mean you're in the clear. The first sign of instability you observe may be the large avalanche you trigger.
Avoiding steep, wind-loaded slopes can significantly reduce your chances of triggering an avalanche. Persistent Slabs can release in surprising ways, break wider than expected, and release above or hundreds of feet away from where they are triggered. Manage your group by riding or crossing steep slopes one at a time, and consider avoiding areas where terrain features like gullies, cliffs, or dense trees could increase the consequences of a slide.
(12/30/2024) This avalanche, in the headwaters of Cabin Ck, likely happened near the end of the recent storm. The avalanche stepped down to mid-December weak layers. Photo: Sawtooth Avalanche Center