Avalanche in the trestle creek area.

Location Name: 
It was in a bowl near trestle creek
Selkirk Mountains
Date and time of avalanche (best estimate if unknown): 
Tue, 02/09/2021 - 11:38
Location Map: 
United States
48° 15' 45.45" N, 116° 11' 3.4872" W

Red Flags: 
Recent avalanche activity
Recent loading by new snow, wind, or rain
Obvious avalanche path
Terrain Trap

Observation made by: Public
Avalanche Observations
Avalanche Type: 
Trigger type: 
Crown Height: 
4 ft
Weak Layer: 
Other - explain below
Avalanche Width: 
1 000ft.
Above Treeline
5 500ft.
Bed Surface: 
Other - explain below
Avalanche Length: 
1 000ft.
Number of people caught: 
Number of partial burials: 
Number of full burials: 
More detailed information about the avalanche: 

This avalanche was huge, it was around 1,000-1,500 ft wide at the crown and varied between 3-5ft in crown height. It was hard to tell how long it was but it ran all the way to the creek drainage below and filled the drainage and pushed snow to the other side of the drainage as well. I would guess the hill was around 1,000 vertical ft tall down to the drainage. 
A pit was dug by 2 guys in our group, and ultimately that was the beginning of things going bad. The pit they dug was not nearly big or deep enough, the isolated column compression test was performed incorrectly and the 2 guys doing it also didn't see that the column broke 2 times and didn't pay much attention when my partner and I called the breaks out. Above and beyond that I was naming off red flags left and right about this area, but these 2 guys were convinced it was safe. The guy who ended up partially buried took off but my partner and I held back because my gut was telling me that all the previously mentioned things were a very bad warning that I should not put myself in harms way. Sure enough, about a minute later I saw what looked like roller balls, but then realized that the guy that took off had remotely triggered an avalanche above him which then propagated across around 800 ft or so towards where I was parked in the thick trees where I had decided I was safe to watch from. Luckily the safe zone I chose payed off and myself and 3 others were not involved in the slide at all. I realized it was a very large avalanche when I saw the giant snow dust cloud that was barreling down the mountain. Fortunately we were able to spot the guys orange avy pack and were able to make radio contact and verify he was only partially buried and was ok. At that point I instructed everyone to carefully one at a time descend back down to the trail to safety, and we sent one guy over to the buried guy to help him get out to minimize further risk of multiple burials. 

The snow from the trigger area slide on what I would assume was a buried surface hoar layer, where as the snow that slide in the area that propagated appeared to be more of a storm slab that my partner and I noticed in the compression test. 


Avalanche Photos: 
Snowpit or crown profile photo or graph: 
Weather Observations
Blowing Snow: 
Air temperature: 
Below Freezing
Air temperature trend: 
Wind Direction: 
Accumulation rate: 
More detailed information about the weather: 

It was a clear cold bluebird day.