Shooting cracks and collapses in West Brush

CBAC CBAC Observations

Date of Observation: 03/08/2022
Name: Zach Guy

Zone: Southeast Mountains
Route Description: Traveled on flat or east facing terrain to 11,400 ft. in West Brush Creek

Observed avalanche activity: Yes
Avalanches: Good views of lots of terrain in West Brush up towards White Mtn, and I did not see any natural activity from this past storm. However, there were a handful of small soft slabs that ran recently near valley bottom near the confluence of Middle and West Brush Creek. One of them appeared to be remotely triggered today by a snowmobile. The rest ran naturally sometime in the past couple days on east and north aspects.
Weather: Mostly clear skies, calm winds where we traveled; occasional light drifting on high peaks like Teo. Cold day.
Snowpack: 12″ of settled storm snow in the Union Chutes area. We saw numerous shooting cracks while snowmobiling flat terrain in valley bottom, a couple of them shook willows or small tree branches. The most interesting one I triggered from across a creek; the failure must have crossed a snow bridge and collapsed the opposite slope (east facing). On skis, we produced two collapses on east facing slopes around 10,000 ft. Both collapses required some hard stomps to punch through the mid-slab crust first. Most of the steep terrain around here avalanched with the last cycle. The one bedsurface we traveled on did not appear to have enough slab to be problematic; it did not produce signs of instability on slope angles up to 40 degrees. I also tested a few south and west facing terrain features without any signs of instability.  Obvious signs of instability also waned as we climbed to near treeline elevations on E/NE, although the structure is clearly poor from pole probing.