Persistent Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Likely
- Size
- 1–2
On Monday, fresh snow and ridgeline winds woke up thelayers of buried surface hoar and facets we've been tracking in the upper snowpack. Mission Ridge Ski Patrol reported widely propagating avalanches on steep wind-loaded slopes that failed on a layer of buried surface hoar.
So far, most of the activity has been localized to wind loaded areas. These slopes will remain dangerous. However, as more snow falls and temperatures warm, all steep open terrain becomes suspect. Long shooting cracks, whumping collapses, or natural avalanches are key indicators of dangerous avalanche conditions. Small, steep test slopes or convex features can help gauge the reactivity of the upper snowpack. But given snowpack variability, be cautious about extrapolating your results too broadly. Instead, dial it back by seeking out low-angle terrain protected from the wind while we attempt to reduce uncertainty around these tricky, persistent weak layers.
(2/23/2026)
A widely propagating and deep wind slab avalanche triggered by Mission Ridge Ski Patrol during control work. This slide is 3-3.5ft deep and failed on buried surface hoar.
Photo: Drew Carleton