Northern San Juan
AvalancheAnonymous · Mar 23, 2024 · Northern San Juan
Weather
It was windy — consistently above 20 mph, with some very strong gusts. It has been windy in the mountains since about midnight the night before (roughly 13 hours). The wind had been swirling, but cornices and loading patterns indicated it had mostly been blowing towards the north/northwest. The day was overcast, so the snow was cold (no thawing/melting observed all day). There had been a few small snow flurries, but no noticeable wind accumulation.
Snowpack
Extremely firm melt/freeze snow in all southerly aspects on the climb up. We also observed some small wind loading on westerly aspects near the ridge line, which we attributed to snow blow over the top of the ridge. Thus wind loading was fairly soft, without noticeably connected wind slabs. This changed as we descended — see avalanche observation below.
Avalanche
We released a small wind slab avalanche at around 11,600 feet on the west slope of Red Mountain Number Three. We had just crossed Red Mountain Number Three’s northwest ridge, from the north face to the west face, at around 11,700 feet. We were navigating a traverse across three gullies, speared by a small ridges. The snow pack on the ridges was very shallow with exposed rocks. We attributed this melting in the prior days, due to their sun exposure. In hindsight, they had also been scoured by the northerly winds. These same winds had cross-loaded the slope, depositing snow on the skiers left wall of each gully (slightly north facing). We crossed the first gully one at a time, with our party of three regathering on the ridge before the second gully. I skied that gully first, making two turns as I traversed to the opposite ridge. In my second turn, I noticed the snow was not soft, wind loaded snow, but instead was very firm and connected. At this time, a wind slab broke under my feet. I skied further to my left (south), to the ridge I was planning to ski to as our next safe stopping spot. From there, we observed the avalanche. The two inch deep wind slab I broke had propagated about 50 feet, across the full left wall of the fully and into the center as well. It ran about 300 vertical feet, entraining more wind loaded snow but not penetrating deeper into the snow pack. The remaining two members of our party descended about 50 vertical feet on the first ridge before crossing the avalanche path one by one to join me on the second ridge. There, we debriefed the avalanche before skiing down the ridge to observe the avalanche debris, and confirm it had not penetrated deeper into the snow pack. Then, we skied as a group to the northwest, eventually exiting the slope via the typical ski route back to 550.