Southern San Juan
AvalancheChris Bilbrey · Feb 26, 2021 · Southern San Juan
Weather
Sunny and cool. Moderate west winds observed at all elevation bands. This contributed to light drifting near and above treeline but no new wind-slab formation - more buffing the snow surface.
Snowpack
We encountered a variety of snow surfaces - firm crust, softer faceting surfaces, and stiff wind-board. Settlement and stiffening of the upper snowpack evident on north through east to south aspects and supportable out of our skis. Despite a stiff upper slab, weak snow still looms mid-pack and closer to the ground. Facets, crust, and a combination thereof exist on east and southeast aspects and we observed sudden collapse failures in CTs below treeline. ECTs produced inconclusive results with some test producing non-propagating results in a layer of facets 20 cm above the ground followed by test propagating with 30 taps. This 7-layer faceted crust structure will be a concern during a big spring warmup. The higher we climbed in elevation, we found a stiffer and deeper upper slab resting above similar weak snow. An east aspect in the alpine produced numerous propagating results in ECTs failing on a faceted crust mid-pack (ECTP 17) and then stepping down with continued taps (ECTP 30) breaking below a 1F layer in 2-3 mm facets. Today's moderate west-northwest winds were sculpting more than drifting near and above treeline - buffering slopes, hardening already hard surfaces, and forming shallow soft slabs directly below ridge lines.
Avalanche
Observed several loose wet slides that probably ran on 2/23. They were all size 1 and occurred on east through south to southwest aspects near and above treeline.