Persistent Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Possible
- Size
- 1–2
Weak layers of snow formed in November and December are buried within the snowpack. The depth of these layers vary drastically, from 1-3 feet in shallow areas to 3-4 feet in deeper areas. These weak, sugary facets are widespread across most aspects and elevations with increased sensitivity in shallow areas above 9000’ that contain a firm cohesive slab. Depth hoar is developing at the base of the snowpack in specific areas.
Dig down in the snow to check how deep these weak layers are buried. In general, weak layers over a meter will be more difficult to trigger. Avoid those wind loaded and shallow areas in the upper elevation to reduce the uncertainty of persistent slab avalanches.
(1/20/2023)
Common avalanche slope. Failed on persistent weak layer 2-3' deep.
Photo: Penterson