Persistent Slabs
- Alta quota
- Limite del bosco
- Sotto il limite del bosco
- Probabilità
- Likely
- Dimensione
- 1–2
A nasty layer of buried surface hoar on a crust is responsible for six human-triggered avalanches in recent weeks, most recently a remotely triggered slide near Tunnel Ridge. Add the widespread collapsing reported over the last two days across the forecast area, and the picture is clear. This layer is widespread, extending to ridgeline, and you should assume it exists — and can produce an avalanche — on any steep, open slope lacking a stout, supportable crust beneath the recent snow.
We don’t need more evidence to shape our travel plans. You are likely to trigger an avalanche if you poke this bear — the question is how big it will be.
In many places, the slab remains thin and soft, and most avalanches have been relatively small. But not all. The 1,000-foot-wide slide on Snowshed last week shows this setup can still produce a large, dangerous avalanche (see video). Near the ridge, even subtle wind stiffening may be enough to support wider propagation.
Recent faceting and new surface hoar will make these slab changes difficult to detect, as differences in stiffness may be below what you can feel with your feet or machine. Give steep, shaded slopes near ridgelines a wide margin, and stay alert in connected lower-angle terrain where a slide from above could reach you.
(2/13/2026)
Riders remotely triggered this slab avalanche while on a nearby ridge. This failed on a buried layer of surface hoar 40cm below the surface. Today, remotely triggering an avalanche is likely to occur on steep slopes where the surface hoar layer is preserved and not capped by a supportable crust. This slide occurred on a NE slope at 6800'.