Northern San Juan
AvalancheAnonymous · Feb 28, 2020 · Northern San Juan
Weather
Calm. Almost no breeze. High 20s at 11,000’. Partly cloudy. Snow surface was beginning to warm, especially on south, southeast and east facing aspects.
Snowpack
Recent firm windslab observed throughout the past several days in this zone, especially on NE/E-facing terrain near ridgelines. South facing slopes in the alpine were beginning to fail later in the day and we observed several D1-D2 avalanches in south facing alpine terrain.
Avalanche
At approximately 10:45 am, we watched from the east ridge as another party of two skiers dropped Yellow Mountain’s northernmost summit, down the looker’s right, above a rocky choke with large cliffs on either side (N/NE aspect, from ~12,800’). Skier One skied to a safety to the lookers left of the choke, less than 100’ down the face. Skier Two began descending and within two turns triggered a large pocket of windslab, which then propagated and entrained a fairly large amount of snow. The crown appeared to be 6-10” deep and about 20’ wide, but ran the length of the steep terrain, about 600’. We attempted to make radio and vocal contact, but got no response. We watched as they carefully made their way down to the basin and skied our without further consequence. Neither skier was caught or carried by the avalanche. The party will likely submit a report themselves, but I just wanted to make the slide common knowledge for other backcountry users traveling in similar high-consequence terrain. I did not take photos.