Persistent Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Possible
- Size
- 3
Upper elevation slopes facing northwest through east will remain the bulls-eye terrain for triggering a slab avalanche that fails on weak faceted snow. Unfortunately, this persistent weak layer takes a long time to heal. As time goes on, the bulls-eye clues like avalanches, cracking and collapsing go away as the snowpack slowly adjusts to it's recent load of storm snow. Don't let that fool you - it's still possible to trigger an avalanche 2-4' feet deep that has potential to kill you. Yes, the likelihood of triggering a slab avalanche has gone down, but the consequence remains the same.
If you find your-self in northerly facing terrain continue to watch your slope angles as well as what terrain is above you. Avoid steep, rocky terrain that is most likely to avalanche. I love riding powder as much as the next person, but right now is not the time to be riding steep exposed lines, especially ones that have old weak snow underneath. Even though the avalanche danger is MODERATE today - you won't find any of the forecasters at the UAC riding steep northerly facing terrain. We will continue to be patient and wait for the snowpack to become more stable.
Photo: From Bruce Tremper's book. It shows how the danger of a persistent weak layer slowly decreases over time. I put an arrow in to show you where we sit currently.