Persistent Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Likely
- Size
- 3
Heavy snow and drifting from the New Years Storm created slabs of unstable snow on slopes with a sugary persistent weak layer buried 2 to 4 feet deep.
In many places, people are likely to trigger large and dangerous avalanches failing on a deeply buried sugary persistent weak layer. Such an avalanche could be triggered remotely, from a distance or below. The persistent weak layer from November is now buried 2-4 feet deep, and any avalanche that fails on it will likely be hundreds of feet wide.
In upper elevation terrain in the Bear River Range areas with a deep snowpack stability has apparently improved. Poor snow structure still exists in many places, but the buried persistent weak layer from November is buried so deeply that it is unlikely a person could cause a collapse. The problem is that a person could trigger a dangerous hard slab avalanche from an area on the slope where the slab is shallower.
And, it appears that there are areas in the Logan Zone where the overall depth of the snowpack is shallower and the snow structure obviously worse. Recent natural and remotely triggered avalanches show this to be the case.
Here's a picture of a part of the crown line of an avalanche from Sunday off Red Pine Ridge. The avalanche that failed on the November PWL either naturally occurred shortly before it's discovery or it might have been remotely triggered by riders on Red Pine Ridge.