Persistent Slabs
- Hochgebirge
- Waldgrenze
- Unterhalb der Waldgrenze
- Wahrscheinlichkeit
- Likely
- Größe
- 1–2
With a fresh snow load, avalanches may fail on buried weak layers, even in sheltered terrain. On sheltered slopes, these avalanches may act more like your average storm slab. However, in wind-loaded areas, they may break widely across terrain features or be triggered remotely. You'll want to steer clear of steep lee slopes near ridgelines, where these avalanches are likely to be much larger.
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, seek out low-angle terrain protected from the wind while the snowpack adjusts to the new load, and we gain more information on the buried persistent weak layers.
(2/21/2026)
In the neighboring Snoqualmie Pass zone, an unintentionally triggered, widely propagating avalanche from 2/21. N, 5500ft. It's unconfirmed, but this slide may have failed on older persistent grains.
Photo: NWAC