Persistent Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Possible
- Size
- 2–2.5
On specific types of slopes, there is potential to trigger a large, hard slab avalanche on the well-developed facets or depth hoar layers in the middle or bottom of the snowpack. These avalanches are most likely to be triggered on the northern half of the compass and where the snowpack is unusually thin and weak. Be cautious of very steep, rocky, or wind-affected terrain with variable snow depths. Choose slopes with a deep and uniform snowpack to reduce your risk. Southerly slopes typically lack the problem due to previous meltwater strengthening the snowpack.
This persistent slab avalanche caught and carried a snowmobiler last weekend on East Beckwith. The avalanche broke on the January drought layer 2 to 3 feet deep in the middle of the snowpack. Note how the terrain has variable depths and shallow areas due to wind effects. (3/8/2025) Photo: Care Flight