Persistent Slabs
- Alta montaña
- Límite del bosque
- Bajo el límite del bosque
- Probabilidad
- Likely
- Tamaño
- 1.5–3
We're facing two disctinct "flavors" of Persistent Slab avalanches:
1) You can trigger 1-3 foot thick slides involving the snow from the past week on both sheltered and wind-loaded slopes. Assume this problem exists on all upper and middle elevation slopes and on shadier, lower elevation aspects. These avalanches will be large enough to bury people. Although the slides will be largest in wind-loaded terrain, it's unusally easy to trigger avalanches in more sheltered, middle elevation terrain.
2) The avalanches described above can "step down" to weak snow near the ground, producing huge, unsurvivable avalanches. In areas where the entire lower half of the snowpack is weak (like near Galena Summit), avalanches have a better chance of failing near the ground. This layer of weak snow exists on all upper and most shaded middle-elevation slopes (W-N-E).
Some facts to help you travel safely today:
- You could trigger avalanches remotely—from flat or gentle terrain below, above, or to the sides of steep slopes.
- They can break well above you, either while you are descending or at the bottom of a slope.
- Avalanches are pulling back into relatively flat terrain above steeper slopes.
- Some recent avalanches were hundreds to thousands of feet wide.
(1/14/2024) Many of the avalanches that failed this week have pulled back onto relatively low angle terrain. The slides in this image are a great example. These avalanches failed on E-facing slopes at 8,100-8,300 feet near McDonald Peak in the Sawtooths.
Photo: Ben VandenBos
