Persistent Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Possible
- Size
- 2–3
This zone sits in the "sweet spot" for hosting a lingering persistent slab avalanche problem. Here, the weak layer of snow near the ground is well developed and exists in many locations. The slab overlying this weak layer is thinner than in the zones to the north and west, which makes it easier for the weight of a skier or rider to trigger. For these reasons, triggering an avalanche that fails on this weak snow remains a possibility today.
The weak snow responsible for this problem was buried in early December on middle and upper elevation slopes that face away from the sun. You are most likely to trigger an avalanche that fails on this snow in very steep, rocky, wind-affected terrain (see photo at right/above). Here, the overlying slab is variably thick which gives you "better" access to the weak snow underneath.
This large, natural avalanche released naturally near the end of the last storm in very steep, rocky, wind-loaded upper elevation terrain in the 4th of July drainage in the White Cloud Mountains.