HUGE collapses

Date of Observation: 12/27/2021
Name: Zach Guy and Eric Murrow

Zone: Southeast Mountains
Route Description: Snowmobiled out Cement Creek to about 10,500 ft, near Hunter Hill trail.

Observed avalanche activity: Yes
Avalanches: Looks like one fresh persistent slab ran with yesterday’s winds. Spotted two other persistent slabs that ran during the Santa Slammer. All of these were on relatively small slopes so  D1.5 in size or less. Nothing significant has hit the road (yet), a few small debris piles in the narrows near the start of Upper Cement Trail.
Weather: Light to moderate snowfall. Light winds in valley bottom.
Snowpack: In windsheltered, below treeline terrain, persistent slab thickness ranged from 2 feet (near Reno Road split) to a little over 3 feet (near Hunter Hill). We observed several rumbling collapses in low-angle terrain. One occurred while I was standing outside of a pit, while Eric was boondocking over a 1/4 mile away. I think he triggered it. It was the loudest and most startling collapse I have ever heard…it sounded like a jet engine. I could hear it approaching from a distance across a wide open slope and watched the slope drop. I triggered another large collapse riding in sparse trees and saw all of the trees start shaking in front of me. Eric was a long distance away and he also heard “what sounded like an explosive detonate”. Stability tests produced hard, propagating results on the 12/6 interface. We rode on or near a handful of relatively small, steep test slopes without triggering anything. The 12/23 facets appear to be rounding and hardening, but the 12/6 depth hoar/ surface hoar falls out of the pit, it is still fist hard and cohesionless.