Today we went to investigate the crown of a recent accident in the Swan Range where a snowbiker was caught, carried, and partially buried. Our planned travel route intended to have minimal exposure by sticking to ridgelines and valley bottoms. Due to a cliff band, we chose to descend a steeper face that was wind-scoured and noticeably thin. We took note of a cross-loaded gully that looked suspect, so we avoided this pocket by staying skiers left and chattered our way down a sub ridge. The sub ridge we skied down had about two feet of snow that varied from wind-scoured snow to a firm crust. The sub ridge had a low risk of triggering an avalanche. We went on to continue our fieldwork and investigated the crown of the recent accident site. More details regarding the accident are found here.
On our return, we made comments about our ascent back up the steeper section. We talked about booting up the sub-ridge but chose to ascend on skins, switchbacking our way up. At the bottom of the face, we commented on the thin, faceted snowpack. The skin up the sub-ridge was fairly challenging with the slick crust. About halfway up, we inched our way out further into the pocket to make our next switchback. The first skier went through, while skier two was on the sub-ridge. I (second skier) went next and made my kick-turn and returned to the sub-ridge. I then looked back downslope and saw that a slab about a foot thick failed and took out the lower part of the path. The slab failed a few feet below the skin track. The debris was not deep enough to bury a person, but injuries would have been likely given the shallow snowpack. After this, we chose to boot up the scoured snow and back to the main ridgeline.
Lessons learned and takeaways:
Estimated time is based on bump in winds along with appearance the crown and debris gave. Both of which looked very similar to an avalanche that occurred on the 19th.
Crossed debris on a SE facing slope. We could not tell exactly where the crown started.
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