Southern San Juan
AvalancheChris Bilbrey · Mar 29, 2022 · Southern San Juan
Weather
Off and on snowfall, sometimes heavy, until about 3 pm. Brief periods of sun had a big impact to the new snow helping it thicken quickly.
Snowpack
We found 12 to 16 inches of new snow above 11,000 feet and along ridgelines. Storm snow was right-side-up and bonding well at the new/ old snow interface. Only minor loose snow sluffing from steeper convexities. We saw little evidence of wind transport near and above treeline, but the wind blew enough to form soft drifts on leeward terrain features. We observed evidence of melt water and moist grains, from our recent warmup, down 40 to 50 cm's below the surface on northeast-facing slopes at treeline. Below that, the snow was mostly dry and layering consistent. In our below treeline snowpit on a north aspect at 11,200 feet, the primary layer of concern consist of moist, rounding grains (4F) about 80 cm deep under a 1F to P- slab. This layer produced sudden planar failures in Compression Test on 21 and 23 taps approx. 5 cm's below the 2/21 dust layer interface. No cracking or collapsing observed on our travels. The re-frozen old snow surface was supportive to skis on multiple aspects and boot penetration averaged 35 to 45 cm's. By the afternoon, the old snow surface buried by recent snowfall felt more supportive than this morning across all elevation bands.
Avalanche
No fresh avalanche activity observed, but visibility into bigger terrain limited most of the day.