Red Flags
Collapsing
Poor Snowpack Structure
Red Flags Comments
A 32 degree slope collapsed, with some cracking visible too, at 8900 feet, WNW facing, while Vert snowshoeing north of the Snowbasin perimeter. Immediately beforehand, the Vert snowshoes were sinking deeper, in a "mushy" feeling area, becoming knee deep with the snowshoes on, instead of boot-top deep. I retreated 20 feet down the fall line to the nearest tree, went on belay, clipped gear to the tree, and dug a pit. This westerly exposure gets some afternoon sun, which, I suppose, had contributed to a thick ice crust near the ground. The snowpack was only 3 feet deep in this area; half the depth of a more north-facing pit I dug earlier this week.
I don't have a diagram of this pit, so here it is verbally.
This spot was about 200 feet down from the ridge, with 10" of fresh powder in the previous 48 hours, much more than the reported 2".
Below that was 7" of firmer slab, 4 fingers in hardness.
Below that was a thin inobvious crust, which formed the top surface of:
about a foot of weak (fist) faceted snow. Ugly. This is what made for the deeper, difficult snowshoeing, for about 4 steps before the collapsing.
Underlaying that was a hard thick ice crust, 4-6" thick, on the ground.
