Quick report
- Slope Angle
- 39°
Avalanche
- Slab Width
- 24 m
- Weak Layer
- Ground Interface
- Trigger Type
- Skier
- Vertical Fall
- 457 m
- Avalanche Type
- Hard Slab
- Slab Thickness
- 61 cm
- Trigger Detail
- Remotely Triggered
- Start Zone Aspect
- Northeast
- Avalanche Problem
- Wind Slab
- Start Zone Elevation
- 2835 m
Skier 1 of 3 was skiing down the fairly firm wind-scoured ridge at the top of Toots to Boot, headed N, ~15 deg slope, and got a big loud collapse. A crack propogated through the firm near-flat ridgetop and across the entry zone of Toots about 80 yards to the far side of the run where it was slightly steeper and the slide released. It went to the very bottom of the run, moving very fast. We later saw evidence of a similar size slide about the same distance away in the other direction off the ridge, N facing and further W (dropping into Bowman Fk). We didn't see that slide, but are pretty sure that it triggered at the same time - it was very fresh when we went around the corner and saw it. Several interesting take-aways:
The crack propagated a long ways across a heavily wind-loaded slopeof at least 35 deg steepness and same exposure without triggering anything else
This was the first collapse we saw today (but not the last). We had been lapping a sub-30 deg NW facing slope prior.
A couple of large cornice falls just S onto a steep, wind-loaded slope, same elevation and aspect, didn't trigger anything
Both slides broke to the ground (repeaters?)
There was no one and no tracks below us that we could see. We were nowhere near being caught but if a party was transitioning or skinning below us without getting well clear of the runout zone, they would have gotten a rude surprise.
The NW facing slope we had been lapping was getting still with windblown snow but the meter or so deep column I isolated at about 8600 ft (below the ridgeline) was pretty stout and I was unable to get a shear plane when I tried to pry it off. We were sticking to a lower angle slope with tres barely open enough to ski but saw no evidence of instability, making me think slopes exposed to direct wind are very different than lee slopes with some fetch. No surprise.
We had joked about picking someone to ski cut that slope. That would have been a Very Bad Idea (we had no intention of actually doing that).
This confirmed that conditions are very tricky right now and, combined with our current lack of low-elevation snow, leave a pretty limited set of options for anyone wanting to do some serious powder riding. This is a good oppotunity to practice patience and very conservative decision-making.