Quick report
On the way up the skin track, ran into the group who dug two pits on the NE shoulder (see other Fish Creek Knob observation from January 2). Decided to go check out their upper pit for a quick look at the persistent weak layer. At 2640’ on a NNE aspect with a 45 degree slope, found a 170cm deep snowpack with a very loose (fist hardness) melt forms/facets layer 80cm below the surface. This weak layer was 22cm thick here, which may help to explain the stubborn propagation test results. Since formal snowpack tests and profile notes had already been done by the previous group, we decided to try the Potato Chip Test taught by Bill Glude (see description in photos). For this test the idea is to manually excavate the weak layer below the slab and observe how the slab fractures. With a ski pole in hand and reaching up to my shoulder, I was able to remove the meltforms/facets layer in a 165 cm radius arch without the slab fracturing. After digging the supporting legs of the arch out, I continued to excavate the weak layer at the ends and finally the slab broke, with clean fast energy. The slab fracture reached 180 cm from the pit wall, 15 cm further than I excavated. This qualifies as a PCT1, a fresh crispy chip. This quick informal test result indicates that the slab is quite strong and has propagation potential when it fails. If snowfall continues to accumulate without cleaning out this persistent weak layer, it may be able to hold a significant load before it fails. With a few relatively deep slab crown lines observed in the region, and a couple propagating pit test results reported, evidence is building for an isolated persistent weak layer that may be with us for the rest of the season.
Avalanche
Relatively deep slab avalanche crown lines observed on the north face of Fish Creek Knob and NW ridge of Showboat. NW Showboat crown ran wide and looked to be similar size, depth, aspect and elevation of the False Troy crown noted in other observations. Crown on N Knob looked similar depth but smaller width.