Date of Observation: 12/10/2021
Name: Zach Guy
Zone: Northwest Mountains
Route Description: Lower Slate, Lower Oh-Be-Joyful. Traveled on NE, SE, and S aspects to 10,700 ft.
Observed avalanche activity: Yes
Avalanches: Nearly every northerly facing avalanche slope that we were close enough to have good views of slid naturally overnight. Where we traveled, most of the terrain was relatively small and slides were D1 to D1.5, one D2. It appears most of Climax Chutes also ran, generally D1.5 to D2.
Weather: Light snowfall through most of the day, with a couple of brief pulses of moderate snowfall. Gusty northwest winds in the afternoon were blowing snow at all elevations. Cold temps.
Snowpack: Widespread collapsing on northerly aspects; some muffled, some rumbling. Shooting cracks on many slopes. The only steep terrain that we felt comfortable traveling on, and without signs of instability, were recent bed surfaces, low elevation southerlies (which were previously bare and without fresh drifting), and dense trees. About 2 to 3 feet of storm snow.
Did this cycle flush the basal facets? In the bedsurfaces that we traveled on, there was a crust or roughed up stiff layer on the sliding interface, with more weak facets below. Enough to provide some structure for modest loading, but I don’t think we’re out of the woods because there are still weak layers hanging on. Time will tell, but I think this cycle only shaved off the top half of our weak layer where we traveled.