Persistent Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Unlikely
- Size
- 3
Think of the snowpack like a material being stressed. When new snow falls, we add load (weight) and the snowpack deforms elastically—it bends and stores energy without failing. Add enough weight, or apply stress in just the wrong place, and the snowpack can exceed its strength and fail suddenly, producing an avalanche. When there’s a break in loading (like days and days of high pressure), the snowpack begins to deform plastically, slowly adjusting and settling into a more stable configuration. As stored stress is released, avalanches become less and less likely over time.
Another way to think about this is to imagine squeezing a spring between your fingers. As you apply force, the spring compresses, changes shape, and stores energy. Loading the snowpack with new snow or wind-drifted snow does the same thing—it compresses the system and increases stored stress. When you slowly ease your fingers apart, the spring relaxes and releases that energy gradually. Similarly, when there’s a break in loading, the snowpack begins to creep, adjust, and settle. As stress is released over time, the likelihood of a sudden failure—like a slab avalanche—decreases, though it doesn’t disappear entirely.
With that said, there’s no doubt we still have a layered snowpack with buried persistent weak layers. It’s been a week since the last reported slab avalanche, which suggests the snowpack is slowly adjusting.
As always, there is inherent risk in the mountains. Continue to be on guard in upper-elevation terrain—especially on thin, steep, shallow, rocky slopes. These isolated areas remain the most likely places where a person could still trigger a slab avalanche.