Persistent Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Possible
- Size
- 1–2
For over two months, our thin snowpack sat stagnant, faceting and rotting under cold, clear skies. Periods of extreme winds in December scoured this thin snowpack and created dense, isolated slabs. This is now the base of our snowpack. This week, 1.5-2.5 feet of low-density snow fell across the forecast area. Recent snow fell without significant wind effect, so slab formation has been slow to evolve, and the new snow is still relatively loose and incohesive on sheltered aspects. Despite this, it will still be possible to trigger an avalanche 2-3.5' deep on old weak snow near the ground, on all aspects at mid and upper elevations.
- Avalanches will be more likely on slopes steeper than about 30°. This is a problem you can manage by keeping your slope angles shallow.
- Avalanches will be easier to trigger on smooth, firm slabs formed in gullies during December's wind, where the terrain could amplify the consequences of even a small avalanche.
- Whumphing and collapsing of the snowpack are indications that there is weak snow failing near the ground. Hand pits and pole probes will help reveal if you're traveling over old, weak snow or firm slabs.
The snowpack has poor structure, little strength, but currently lacks much energy. Dry loose avalanches are possible on steep, upper elevation slopes where the new snow didn't sluff off during the storm. With increasing winds, be on the lookout for drifting snow, as this could easily stiffen the new snow and increase instabilities.
Good travel protocol can help limit the consequences of an avalanche. Travel one at a time, choose safe points to stop, and keep eyes on your partners.
(1/8/2026)
A party triggered this avalanche on Microdot Bench Wednesday.