Southern San Juan
AvalancheChris Bilbrey · Dec 6, 2022 · Southern San Juan
Weather
Snowing and blowing throughout the day. Snowfall ranged from S1 to S2, and winds were moderate out of the southwest gusting into the 30s.
Snowpack
The snowpack gremlins were very talkative today and snowfall over the last seven days has incrementally added stress to fragile grains below. We observed extensive shooting and en echelon cracks and rumbling slope-wide collapses on near and below treeline slopes throughout the day. Warning signs of unstable snow occurred on all aspects except south and southeast. On those slopes, a stout crust below more recent snowfall was the most notable difference in snow layering in the upper snowpack. The overlying slab above 4F- faceted grains ranged 30 to 40 cm thick across slopes. Thickness of faceted grains ranged 10 to 15 cm. The slab, weak layer combination produced sudden planar failures in Compression Test and propagated failures in Extended Column Test with easy-moderate force.
Avalanche
We remote triggered 3 slides (size 2) and one sympathetic slide (size 1.5) while walking along the top of the ridge. We triggered one slide from around 30 feet away and the other two from around 150 feet away in a clamshell depression. The sympathetic slide was about 300 feet around a terrain feature in thicker trees.