Persistent Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Possible
- Size
- 1.5–2.5
It is possible to trigger 1.5-2 foot thick slabs above weak layers of facets or face+cust combinations. You are most likely to find trouble on steep middle and upper-elevation slopes facing the northern half of the compass. Signs of instability like snowpack cracking and collapsing (whumpfing) may not be obvious, and your first sign of instability could be triggering an avalanche. Avalanches could be triggered remotely, from lower-angle terrain above, below, or to the side of steep slopes. Persistent Slabs can release in surprising ways and break much wider than expected.
You can manage this problem by seeking lower-angled terrain free of terrain traps such as thick trees, gullies, and cliffs.
(3/19/2025) Slab avalanche above Rainbow Lake N 10,000'. White Clouds. Photo: Sawtooth Avalanche Center