Persistent Slabs
- Alta quota
- Limite del bosco
- Sotto il limite del bosco
- Probabilità
- Likely
- Dimensione
- 3
It's been about 10 days since the last storm and avalanche cycle. Red flag signs of instability such as collapsing and cracking are no longer evident but poor snowpack structure remains. In spite of the warm temperatures and misleading snow surface, layers of weak faceted snow still exist underneath. On northerly aspects near and above treeline, thick hard slabs 2-4 feet thick exist over these persistent weak layers. Although becoming more stubborn to release, when they do they are capable of taking out the entire season's snowpack. Likely trigger points include thin, rocky areas, steep convexities, and areas along slope margins but my strategy continues to be avoidance of steep slopes in these areas entirely.
Results of an extended column test on a northeast aspect at 10,800 feet, at the upper end of our "below treeline" elevation band. Score was ECTP25 failing on the Feb 11, persistent weak layer. This indicates that avalanches are growing more stubborn to release, but that they are still clearly possible. It's getting to where finding the right trigger point, such as a shallower area on the slab is what it will take. The danger increases with elevation.
