Persistent Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Possible
- Size
- 2–3
It's been nearly five days since the snowpack in this area has been stressed by a significant loading event. Unfortunately, the type of weak snow that we’re dealing with this year isn’t the sort to heal quickly. Although very little snowfall has been recorded in the past days, the snowpack continues to give us clear signs that it is unstable.
Yesterday, in the Baker Creek drainage, I observed a slab avalanche that appeared to have failed naturally that day (photo at right). Sun Valley Heli Ski staff reporting seeing a large avalanche that likely failed sometime on Saturday (photo here). Both of these avalanches are clear indicators that triggering slides on our buried persistent weak layers continues to be a worrisome possibility.
You can reduce your exposure to the hazard posed by this problem by choosing gentler slopes and avoiding terrain where the wind created slabs during and following last weeks storms and added stress to the weak snow underneath.
ADDITIONAL DISCUSSIONAging wind slabs in exposed upper elevation terrain are becoming less reactive as time passes. However, if you do trigger one of these smaller slabs it may be capable of triggering a more sizable slab as it travels downhill. This appears to be what happened with the avalanche that Sun Valley Heli Ski staff reported seeing yesterday (photo above).