Persistent Slabs
- Hochgebirge
- Waldgrenze
- Unterhalb der Waldgrenze
- Wahrscheinlichkeit
- Likely
- Größe
- 3
Poor snowpack structure remains widespread on slopes facing west through north to east. The 2/11 persistent weak layer is now buried beneath 22 inches of recent snow. On some below-treeline slopes, this new snow has formed a cohesive slab, and skiers and riders can still trigger soft slab avalanches. The danger increases with elevation, where thicker, more cohesive slabs rest above the weak layer. The greatest concern is on slopes that previously held wind-drifted snow, where hard slabs 2 to 4 feet thick now rest above weak facets. Human-triggered avalanches remain likely, and any avalanche may step down to deeper weak layers, as confirmed by recent field observations. Avalanches failing on the 2/11 weak layer are large enough to bury a person, and deeper step-down avalanches could release the entire season’s snowpack, resulting in destructive and deadly avalanches.
Obvious signs of instability, such as collapsing and cracking, are becoming less frequent. Do not let the lack of obvious red flags create a false sense of security. Many steep slopes did not avalanche during Friday’s storm and remain primed for release. The weak layer is still sensitive, and these slopes remain poised for a trigger. The safest strategy today is to avoid slopes steeper than 30 degrees.
