Persistent Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Possible
- Size
- 1.5–2.5
Slabs overlying weak layers buried 2-3 feet deep remain possible to trigger on very steep slopes over 35°. Signs of instability such as cracking, collapsing, or recent avalanches may not be present before triggering a large, dangerous avalanche that is capable of propagating far across or upslope. Multiple tracks on a slope do not indicate that a slope is stable. Stick to lower consequence terrain away from terrain traps and rocky, convex, very steep slopes today.
A large wet slab avalanche was reported to have occurred 2 days ago naturally on an East aspect at 8500 feet in Dry Creek in the Salt River Range. This avalanche likely failed at an interface involving a persistent weak layer and occurred during the heat of the day. With overnight cooling and increasing cloud cover today, expect this type of avalanche to be less likely but not impossible. This avalanche is an example of a persistent slab problem. The potential trigger today would more likely be a large group or cornice impacting a slope rather than heat and sunshine.
(2/20/2025)
This photo depicts one specific type of terrain where the persistent slab problem is relevant.
Photo: Alex Drinkard