Southern San Juan
AvalancheChris Bilbrey · Nov 27, 2023 · Southern San Juan
Weather
Abundant sunshine and a light breeze.
Snowpack
Snow that fell on November 24 and 25 makes up the majority of snowpack depth and structure. On southerly aspects, this mostly sits on the ground, or directly above the couple of inches of snow that fell on November 19 to 20. On east-facing slopes, we found a 10 cm layer of faceted grains below the latest storm snow. This weak layer took moderate force to fail in tests. By far the most concerning hard-over-soft structure we found on our travels exist on northerly-facing slopes near and below treeline. We did not travel into the alpine, but assume a similar structure exist with deeper wind-drifted slabs. The bottom 15 to 25 cm of the snowpack on northerly aspects consist of October hold-over snow and the small storm on November 19 and 20. Both basal layers consist of large grain facets/ depth hoar (2-4 mm) and are generally F to 4F- in hardness. This layer failed with easy force in Compression and Extended Column Tests. While the overlying slab was mostly supportive to over-the-snow travel, we noticed faceting throughout likely driven by shallow depths and continued cold temperatures.
Avalanche
The few slides we saw occurred on north and northeast aspects near treeline.