Persistent Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Possible
- Size
- 2
The Saturday/Sunday storm did not seem to be enough of a load to stress the Jan/Feb drought persistent weak layer (PWL), but there remains the possibility of triggering an avalanche 1-2' deep that fails on this layer of faceted snow in localized terrain at the mid and upper elevations on slopes facing west through north and east. Sunday's avalanches in Summit Park (photo below) and in the Memorial Couloirs are perfect examples of this type of isolated terrain.
On Sunday, I was in Millcreek Canyon, returning to terrain that I had visited the week prior. When I was there on 2/26, I could not find a stronger slab on top of the Jan/Feb layer of facets. But on Sunday, I was now finding a denser/stronger slab due to settlement and warm temperatures this past week and I was able to get cracking in the slab with failures down 12-16" in the layer of faceted snow. The take-home message for me is to still assess each slope where the PWL is present - even if I know that there had been no slab prior.