Persistent Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Possible
- Size
- 1.5–2.5
The Valentine's Buried Surface Hoar layer, along with weak faceted snow around the 2/8 interface, has been found in the upper 3 feet of the snowpack. If you trigger a slab avalanche on either or both of these fragile weak layers, you will likely produce a large to very large avalanche. Unfortunately, you will likely not observe Red Flag warnings to alert you that weak snow is beneath you. This is not an avalanche problem that can be managed, like smaller storm and wind slabs.
Sticking to simple terrain and avoiding traveling beneath steep slopes is our best advice. Continue to monitor the observations and read the entire forecast daily. This problem is not going to go away overnight, and trying to outsmart it could be dangerous.
Persistent Slab avalanches can release in surprising ways:
- They can be much wider than expected
- They can break above you and pull into relatively gentle terrain.
- You can trigger them remotely—from flat terrain below, above, and to the sides of steep slopes.
(2/26/2026)
2 Natural Avalanches observed near Pine Lakes in the Southern Wallowas.
Photo: Victor McNeil