Persistent Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Likely
- Size
- 1.5–2.5
Two separate persistent weak layers are buried under recent snowfall from the past two weeks—these range in depth from 1.5 to 4 feet.
- Sunday, the 15th, a layer of surface hoar and near-surface facets was buried along with melt-freeze crusts on solar aspects. This persistent slab problem has been very active in recent days and is now buried 1.5-2.5 feet deep. You're most likely to encounter this problem at the middle and upper elevations, across aspects ranging from W-SE.
- Two weeks ago, on the 8th, our month-long dry spell came to an end, and all that weak snow was buried. This persistent slab is much deeper, ranging from 2 to 4 feet deep. Triggering an avalanche on these deeper weak layers is becoming much more difficult, but an avalanche would be large and destructive. You're most likely to encounter this deeper, persistent slab on NW-N-NE slopes above 6,500 feet.
We've received multiple reports of people remotely triggering (from above, below, or on adjacent slopes) persistent slabs. Both of these persistent slabs have shown the potential to propagate long distances and catch people by surprise. As more time passes since the last major storm, you may not receive any clear feedback (such as cracking, collapsing, or whumpfing) before an avalanche. The weight of a snowmachine is much more likely to affect buried weak layers than a person's weight.
(2/19/2026)
Participants in the Motorized Level 2 class spotted these avalanches on Thursday (19th). On the right side of the photo, two cross-loaded terrain features slid naturally, likely on recently buried PWLs.
Photo: Payette Avalanche Center