Persistent Slabs
- Hochgebirge
- Waldgrenze
- Unterhalb der Waldgrenze
- Wahrscheinlichkeit
- Unlikely
- Größe
- 2–3
Warm and dry weather over the past 2 weeks has caused our persistent layers to go "dormant"—a state where they're unlikely to produce avalanches unless a major loading event occurs. But it's important to remember that these weak layers still exist beneath your feet or sled. The most prominent is the early-season facet layer that's buried 3-4 feet deep (photo above/right).
As long as the poor snowpack structure exists, there is still a very small chance of triggering a persistent slab avalanche. This leaves you two choices: accept this slight chance, or avoid areas where they are more likely to occur—very steep (approaching 40 degrees), rocky, wind-affected slopes. Terrain like this is most common at upper elevations and especially in the alpine.
(3/11/2021) Weak layers may be dormant, but they still exist. This snow profile shows soft snow near the surface that steadily hardens until the weak facets carved out near the ground. Photo: J. Preuss