Northern San Juan
AvalancheNicole Lawton · Dec 11, 2021 · Northern San Juan
Weather
Clear and full sun with temps increasing rapidly throughout the morning from around -1 at sunrise to ~22 degrees at the time of avalanche. 11,352' on an E/NE aspect.
Snowpack
As we all know, our zone received a significant load (approx. 25" from the storm cycle) over the course of 48 hours, on top of a very weak and shallow snowpack with well developed facets. One of the skiers in our party had dug a snowpit the day prior on a similar aspect and elevation to our objective, receiving the result of ECT6 Q1 on a crust-facet combo 22 cm from ground. (Another large red flag, this obs was also reported to CAIC). The avalanche we unintentionally triggered appeared to run on this particular weak layer, not to the ground.
Avalanche
I (Nicole) skied first down the upper part of the run, stopping before a roll where we all regrouped. We decided the safest route was to stick to more southerly aspects that didn't have snow before the storm, as we had already witnessed clear signs of instability, especially on the northerlies. We were able to work the terrain with no whumphing or cracking through the first pitch of our descent. At the top of the run, I stopped and radioed to the other skiers. Skier 2 (Kaylee) skied the pitch next without consequence, and came to an abrupt stop above me. Her edge going into the snow with a bit of force caused a whumphing collapse with shooting cracks across a flat bench approximately 50' away to the rollover at the top of the next pitch. We looked that direction and observed a large powder cloud, running down into the gully below, entraining the entire run we had intended to ski. We quite couldn't observe the whole scope of the avalanche from above. We immediately got on the radio and notified any other parties in the area of the avalanche and that all in our party were accounted for. We continued to work more low-angle, south-facing, heavily treed terrain adjacent to the run. Eventually to avoid more suspect slopes we skied traversed to ski the bed surface to a low-angled meadow below at approximately 10,500', able to exit back to our initial skin track without any more avalanche activity. The avalanche ran approximately 700' (from approximately 11,500'-10,800') and was approximately 350' wide. We didn't get a very close look at the crown, but it appeared to be approximately 60-80 cm (up to 2.5' deep). It entrained the full width of the path to the edge of dense trees. Estimated D2/R2. Soft slab. Unintentional remote skier triggered.