Persistent Slabs
- Alta montaña
- Límite del bosque
- Bajo el límite del bosque
- Probabilidad
- Possible
- Tamaño
- 1–2
Slabs exist above widespread, weak layers (facets, surface hoar, crusts, and combinations). Persistent Slab avalanches are most likely in thinner snowpacks around the Wood River Valley. Before triggering an avalanche, you may not experience obvious signs of instability like snowpack cracking and collapsing or whumpfing. Persistent Slabs can release in surprising ways and break much wider than expected. You are most likely to trigger a dense, 2-4 foot thick avalanche where:
- The snowpack is less than 4 feet thick—relatively shallower spots may exist where the wind frequently blows, and the slab is not uniformly thick.
- Any part of the slope you are on or connected to is steeper than about 35 degrees
- The slope faces the northern 2/3 of the compass
- A smaller wind slab or loose snow avalanche overloads the buried weak layers
Additional Discussion - Wind Slabs: Near Dollarhide and in the Soldiers, look for sensitive wind slabs near ridgelines and along steep mid-slope gullies. You can reduce your chances of triggering a wind slab by avoiding slopes with obvious signs of wind-loading, such as new cornice growth and large dunes or pillows of wind-blown snow. Cornices are large and may be unstable. Warming temperatures may cause overhanging cornices to sag and fail. Limit time beneath these features and give them a wide berth when traveling along ridges.
(2/18/2025) A skier on Patterson Pk near Hailey triggered this large avalanche. After several turns on the slope, the slide broke above and around them. Thankfully, the skier was able to ski ahead and to the side of the slab. NW @ 8,050'. Photo: Sawtooth Avalanche Center