Deep Persistent Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Likely
- Size
- 2.5–3
Consistent snowfall through the majority of April has built a slab that is unstable at upper elevations. The depth and type of weak layer is highly variable ranging from 2-5 feet in depth dependent upon location. Before yesterday this layer was thought to exist on just shaded aspects. Numerous natural slab avalanches on solar aspects occurred yesterday, proving this theory incorrect. This weak layer is more widespread than previously thought, the weak layer type and depth is variable. On shaded aspects, faceted snow exists that was created during the extended March high pressure. On solar aspects a melt freeze crust is acting as an effective bed surface with small wet loose producing natural slab avalanche activity during the day yesterday.
This variability in the weak layer shows that the steady buildup of snow during April without solar input is the main issue. One sunny day and a clear night is not enough to significantly lower the hazard with this unique situation. Dangerous avalanche conditions are expected to continue today.
There is plenty of moderate terrain in our forecast area where users can enjoy the new snow without worry of triggering a dangerous avalanche. Steep and complicated terrain is the major area for concern today.
It is strongly encouraged to keep terrain choices moderate and simple.
(4/15/2025)
Hiker triggered avalanche on Local Spines . Crown depth 3-4 feet/ 500-600 feet wide/ multiple step downs.
SS-AFu-R3-D3