Persistent Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Very Likely
- Size
- 4
Buried under the newest storm snow is a weak layer of faceted snow. This weak snow has now been and will continue to be overloaded creating dangerous avalanche conditions. Avoid being on, underneath, or adjacent to slopes steeper than 30° in steepness. Avalanches involving persistent weak layers (PWL's) can be triggered remotely (from a distance).
Photo of an avalanche with an unknown (possibly remote) trigger on a north aspect at 7,500'. This was on Cutler Ridge and was 2' deep x 125' wide.
If water were to percolate down to persistent weak layer at lower and mid elevations then it will create a problem. This is a localized problem as many of these locations had little to no snow before this most recent storm. They may catch a rider trying to avoid higher avalanche danger at upper elevations.