Persistent Slabs
- Alta quota
- Limite del bosco
- Sotto il limite del bosco
- Probabilità
- Possible
- Dimensione
- 1.5–3
Weak facets and buried surface hoar sit below a 2 to 3 foot deep hard slab. The likelihood of triggering a slide that breaks on this layer has been decreasing daily, but it is still possible and the consequences are still serious. Shaded slopes steeper than 35° degree, above 8,000 feet and below the exposed alpine is where you could encounter this problem. Avalanches failing on this layer are difficult to trigger and signs of instability will likely not be present. Be diligent with your terrain assessment and wary of steep slopes where this weak layer exists.
Take a look at this avalanche triggered two days ago in Prater Canyon. This is a good reminder that it is still possible to trigger a persistent slab avalanche.
(3/8/2026)
Prater Canyon - North 8300’ (X=Snowmobile)
This avalanche was triggered yesterday on a sheltered slope which had a skin and ski tracks on it.