Persistent Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Possible
- Size
- 1–2
There is a chance a person could trigger an avalanche around 1’ deep on a layer of buried surface hoar. We are seeing red flags such as whumpfing/collapses and shooting cracks on this layer which is telling us that if the slope was steep enough we could have triggered an avalanche. This type of weak layer is notorious for taking months to heal which is unusual to a lot of us. Usually weak layers tend to gain strength faster but this has not been the case for this layer.
A new development is that a stout crust has formed on the surface up to 2,000’ which can make us feel safer. The truth is that we are unsure how true this is, especially if the crust is thin in some spots, doesn't freeze overnight or melts in the afternoon. Do not bet this crust will keep you safe. We still have a weak layer under a slab that is capable of triggering an avalanche.
It has been very difficult to feel good about traveling on this layer. In Turnagain Pass people have triggered avalanches above them from relatively flat terrain as well as on slopes with many tracks on them. If you do decide to venture into steep terrain, look for slopes that fan out and do not have terrain traps where snow can pile up such as gullies or creeks.