Persistent Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Possible
- Size
- 1.5–2.5
The persistent slab problem is found on all elevations and primarily on west through north through east aspects. The snow at the base of the snowpack remains weak and is now 2-3 feet below the surface. Use caution around steep, rocky, or wind-affected terrain. These areas often have a thinner snowpack, increasing your likelihood of impacting a buried weak layer. As you travel, take time to dig or probe to identify snow depth and the presence of weak layers. Hard snow over soft snow indicates a buried weak layer. Remember, persistent slab avalanches may be triggered remotely from below, above, and to the side and may propagate in unexpected ways. When in doubt, stick to low-angle terrain under 30 degrees.
Light snowfall and wind over the past couple of days have caused cornices to continue growing. Cornices can break unexpectedly and may act as a large trigger impacting deep weak layers. As temperatures rise through the day, the likelihood of triggering a cornice or slab increases. Minimize time spent on slopes with cornices overhead.
(2/20/2024)
Recent avalanche activity near Angle Mountain on a SW aspect.
Photo: Gabrielle Antonioli