Persistent Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Likely
- Size
- 2
A weak shallow faceted snowpack that existed before this recent snow will struggle to adjust to the added weight and new cohesive slabs that are forming on the surface. Strong SW winds over the last 24 hours have easily transported and loaded slopes. We are extremely well connected and uniform with our weak layers in the snowpack. Adding a more uniform slab on top of this structure will increase the likelihood of triggering an avalanche into these buried weak layers.
Persistent Slab avalanches will have the potential to be triggered remotely from a distance and from lower angled terrain. Pay attention to obvious clues like loud audible whumfs and shooting cracks. These avalanches could be large enough to bury, injure, or kill a person. Avoid being on or connected to slopes greater than 30 degrees today. Below treeline, these avalanches will be smaller but can gouge and entrain the older weak snow creating a potentially dangerous avalanche that could drag you into trees, rocks, or terrain traps.
An overall weak shallow snowpack prior to the storm is just missing the addition of a more cohesive slab to produce destructive avalanches.