Persistent Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Possible
- Size
- 2
The most suspect terrain this morning is isolated to true north and northeast aspects, where soft slabs are breaking at the new snow old snow interface. Especially in areas that received higher water numbers, such as Powder Mountain.
A cohesive soft slab 6 to 12 inches thick sits over the weak, sugary facets that formed during the January drought. Hand pits and test slopes make the structure obvious: dense new or wind-drifted snow resting on top of weak facets. It is not a complicated setup, and it remains unstable. Human-triggered avalanches are still possible today on steep northerly-facing terrain at the upper elevations and on northwest through northeast aspects at the mid elevations.
That said, the underlying weak structure still exists on all north half aspects. With additional loading expected next week, this problem could easily expand back onto a broader range of terrain.
Cracking and collapsing will likely be less common today, and that limited feedback can create a false sense of security. These slabs can still fail on the persistent weak layer and may be triggered from a distance. Treat all steep north half terrain with suspicion, especially slopes that have seen recent wind loading.