Quick report
- Cracking
- widespread
- Collapsing
- widespread
We have seen four large, destructive remotely human-triggered avalanches in the past four days, and similar slides are likely again today. Avalanches will be larger and more destructive as you gain elevation and move into wind-affected terrain and can pull back into lower angle slopes above. Our snowpack is complex and unstable — treat it with respect and build in wide safety margins.
Widespread cracking and collapsing, even in old-growth timber. Regularly saw collapses knocking snow off of vegetation up to 60' away from me densely vegetated areas, with cracks / collapses travelling uphill of me on low angle meadowed slopes over 100'.Weather
- Cloud Cover
- obscured
- Wind Loading
- previous
- Rain Elevation
- 8400'
- Recent Snowfall
- 10-15
- Snow Avail For Transport
- moderate amounts
While riding up the drainage I was intermittently in a cloud, with visibility varying between 50' and 200'. From when I left the truck around 11:30am until 2:30pm, precipitation was varied between light and very light (S1 to S-1), with temperatures making it fall as a mix closer to sleet up to 8500'. Winds were variable and sustained on the upper end of light, gusting moderate at ridgeline. Precipitation ceased at 2:30pm, and some sun breaks provided nice lighting while along the ridge. On the ski down a very thin drizzle crust, eggshell-like in character, had formed from the precipitation. 10-15cm of fresh snow was present from this most recent pulse of moisture.
Snowpack
Riding up the drainage from the truck, travel was mostly straightforward off tracked snow, as the moisture from our rain event the day prior had settled the snowpack, and the crust was mostly supportable. Traveling on skis from 7600', the rain crust was present and supportable up to 8400', with 10-15cm of fresh snow on top. Climbing up the ridge, widespread cracking and collapsing kept me out of avalanche terrain and within old-growth timber. Gaining elevation, I was able to observe 5 D1-D2 avalanches along the ridge I traveled that mostly appeared to initiate naturally on the 1/6, with one appearing to have started as a natural wind slab that stepped down to the 1/6. The snowpack was without a doubt touchy, with very little time passing during my walk without either a crack, collapse, or avalanche pulling my attention.
Conscious of creating a large margin while walking over a large wind-loaded avalanche path near 9300', I was surprised to not trigger it. About 300' horizontally along the ridge from there, and out of sight, I experienced a loud collapse and deep rumbling, but heard no trees snap. Upon returning past this path on my descent, I had remotely triggered a very meaty D2 that ran to valley bottom. This is a perfect demonstration of how the snowpack can present no signs of instability locally near a potential location for a slide, but then produce a large, destructive avalanche from far away.
Avalanche
- Size
- D3
- Count
- 4
- Aspect
- E
- Trigger
- N
- Elevation
- 9200 ft
Walking along the ridge near 9300', I experienced a very large collapse and deep rumbling but could not see an avalanche happening, nor hear any snapping of trees. After reaching my high point and starting my descent, a large slide path 300ft away and just out of view from where I experienced the collapse/rumble had run on a WSW aspect. The path was undisturbed when I skinned past it 5 minutes earlier. Due to the recurring nature of the path, there were no trees to snap, explaining the lack of noise. I had remotely triggered a large D2 avalanche that ran to the valley floor. Skiing down a sub-ridge, I observed an .5mi long crown of a slide on the ENE-facing side of the ridge that had ran on the 1/6 to the valley bottom. I observed close to 15 large D2's, and 2 D3 slides from my vantage on the ridge around the drainage, with many D1's that had ran in the past 5-6 days — most of them occurring in the last 72hrs. These mostly appeared to run on the 1/6, however 2 were suspect to have ran to the ground on 11/30 after stepping down.