Persistent Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Possible
- Size
- 2–3
This zone has been the "not so sweet spot" for the persistent slab problem. The faceted snow near the ground has been especially weak here, and the 2.5-4' thick slab is both thick enough to produce large avalanches and thin enough that our weight can impact the weak layer.
It's been two weeks without an avalanche, substantial loading, or notable snowfall. Can you ski and ride most slopes without triggering a large persistent slab avalanche? Yes. Would I be surprised if someone triggered a slide? Yes. Would I be totally shocked? No.
The poor snowpack layering that exists on most shady slopes (NW-N-NE-E facing) at middle and upper elevations continues to give local professionals and savvy backcountry riders pause. To reduce the chances of finding trouble, avoid "prime-time" slope angles (35-45 degrees) in rocky, wind-affected terrain (see photo).