Persistent Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Very Likely
- Size
- 2
New snow will continue to stress deeper weaker snow layers Sunday night and Monday. Slab avalanches may fail within new storm layers or break down 2 feet or more to weak snow over the 1/13 crust. Persistent slab avalanches are very dangerous, surprising, and difficult to predict. They can propagate widely across terrain features and can result in large and deadly avalanches. Make sure to stop and regroup in places that are well away from and out from under avalanche paths. Stay alert to signs of instability such as recent avalanches, shooting cracks, and whumphing collapses.
(1/30/2021) Human triggered persistent slab avalanche stepping down to 1/13 crust. Estimated to be size D1.5. North facing aspect near Victoria Overlook. Photo: Ashley Turcotte - NPS