Persistent Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Unlikely
- Size
- 1.5–2.5
Your odds of triggering a dense, 2-5 foot thick slab avalanche are low but not zero. You may still find this problem in isolated areas on slopes facing the northern half of the compass, where the wind frequently blows and the snowpack depth is variable. Avalanches are easier to trigger in thin spots at the edges of slabs. Here are some visual clues to identify suspect slopes:
- Wind-pillows, and textured surfaces where the wind has moved snow
- Rocks sticking out of the snow and wind-scouring along mid-slope gullies
Remotely triggering an avalanche from flat terrain near steep slopes remains a possibility. If you do trigger an avalanche, you probably won't observe obvious signs of instability like snowpack collapsing or cracking beforehand.
Additional Discussion: Loose snow avalanches are possible on very steep slopes facing the sun. These often initiate near exposed rocks. Most will be small, but some may grow large enough to bury you beneath large slopes and in funneled terrain. You can reduce your risk by limiting your time spent beneath sun-drenched slopes that look like this, especially during the heat of the afternoon.
(1/11/2025) We observed this recent wind slab avalanche above Dollarhide Summit in an obviously cross-loaded gully. We estimate that it failed on January 8/9 during peak winds. There may also be evidence of a refilled, deeper persistent slab avalanche along the ridgeline. Photo: Sawtooth Avalanche Center