Persistent Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Very Likely
- Size
- 2–3
Observations the past few days make it abundantly clear that triggered avalanches are very likely on and below steep slopes. These slides are breaking two to three feet deep, with some crowns extending over a thousand feet. Riders are triggering them from hundreds of feet away, from flatter ground above, below, and near avalanche terrain. They are failing on a layer of buried surface hoar sitting on a slick crust (the surface left by the January Drought). This problem is widespread and not confined to obvious start zones—small, seemingly benign features can produce dangerous avalanches.
While this is the primary concern on shaded slopes, a second persistent weak layer may exist on sunny slopes. This is a more recently buried layer of surface hoar (2/14), also sitting on a hard crust. It may have been the culprit in a recent snowboarder-triggered slide on a south aspect in the southern Whitefish.
The takeaways: we are running out of safe real estate for playing. Slope angles are the answer for enjoying today’s sun and soft snow. Stick to low-angle terrain with no overhead hazard, where riding conditions remain excellent.
(2/21/2026)
A rider sits at the crown of a large (D2.5) remotely-triggered slab. The avalanche failed on the January Drought Layer (surface hoar sitting on a crust).
