Persistent Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Possible
- Size
- 1–2
You can trigger a dangerous avalanche that breaks on weak snow buried near the ground. The most dangerous slopes are near the treeline on wind-loaded terrain features. Here, there is a cohesive slab of snow around three to five feet thick that can break on the very weak snow near the ground taking the whole season's snowpack with it. Above the treeline, many slopes are wind-scoured to the ground but you can still trigger a dangerous avalanche on features that hold continuous snow coverage such as a gully or a couloir. Safer travel options can be found on wind-sheltered slopes at lower elevations and by avoiding travel on or underneath slopes steeper than around 30 degrees where you find strong over weak snow.
On January 7, 2023, two snowmobilers died in a large avalanche near Corona Pass. You can read the preliminary accident report here. Our deepest condolences go out to the family and friends of the people involved in this tragic accident.