Persistent Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Possible
- Size
- 1–2.5
Early-season persistent weak layers in the lower snowpack are widespread throughout this zone. Most pits show that these weak layers do not tend to propagate a crack though wind loaded locations are likely to be an exception. Despite having such a poor overall snowpack structure, very little avalanche activity has been noted or reported in theis zone. This is likely due to observation bias--so continue to send us your observations! This zone has very weak snow buried 2 to 4 feet deep on most middle and upper-elevation slopes. Digging a pit can easily identify most of these layers, and stepping off of a sled or probing for depth can also help identify weaker snow. Where stiffer slabbier snow exists over the weak layers is where you are most likely to find unstable snow.
(2/5/2023)
This recent avalanche failed on weaker snow near the base of the snowpack.
Photo: Dawson Hatch