Southern San Juan
AvalancheChris Bilbrey · Feb 25, 2023 · Southern San Juan
Weather
High thin clouds kept temperatures on the cool side of things. Winds were strongest along ridgetops but not to the degree as during the last storm. Generally calm conditions near and below the treeline.
Snowpack
Today's high thin clouds and light wind kept snow surfaces soft and cold at upper elevations across aspects. Sunny slopes below the treeline got warm/ wet enough to form a noticeable crust once shaded from the sun in the afternoon. In general, snow depths from the latest storm were deeper near and below the treeline (50 to 70 cm) than above the treeline (30 to 45 cm). This is likely influenced by the strong to extreme winds experienced over the past several days. Alpine areas sheltered from the wind had more similar new snow depths as lower elevations. We observed good bonding at the new/ old snow interface on many aspects and found little evidence of Wind Slab avalanche problems. The strong winds had more of a wind-pressing influence versus slab formation. Southwest and west-facing slopes were mostly scoured of new snow. Snowpack tests on a southeast aspect above the treeline produced non-propagating results in storm layering and in a layer of rounding facets below a 3 cm thick crust with moderate force (13 and 16 taps respectively). The most notable snowpack test result occurred on a northwest aspect around 10,200 feet. We observed resistant planar results in CTs with 24 taps failing in a 1F- layer of faceted snow grains buried around Valentine's Day. No cracking or collapsing observed on our travels or while side-hilling small test slopes.
Avalanche
With vast views of a lot of terrain, we did not see one crown line across the landscape. We did spot one small loose snow avalanche that likely ran the afternoon prior when the sun poked out immediately after snowfall ended. This was on a south aspect above the treeline on a steep area of the slope below a cliff.