Southern San Juan
AvalancheAnonymous · Apr 3, 2020 · Southern San Juan
Weather
Another beautiful, bluebird day in the mountains. Temps remained fairly cool to mild all day, sunshine was plentiful as skies were clear, and winds were consistent but generally light from the SW with some moderate gusts, especially above treeline.
Snowpack
The snowpack received a much needed, thorough freeze last night, on south and southeast facing slopes below and near treeline there was a very firm and fairly thick surface crust that was only noticeably breakable near trees and rock outcrops. The surface was very slow to warm through mid-morning. When we reached south aspects above treeline, we found the crust to be slightly more edge-able and and beginning to slowly soften. Boot pen never exceeded ankle deep, even near the top on a slightly more SE facing terrain feature that had been receiving sun longer than the rest of the primarily south facing slope. We dug a snowpit, 90 cm deep, on a 30 degree SSW facing slope, just above treeline at about 11,300'. Near the bottom of our pit we found two ice layers sandwiching a knife hard crust that was surrounded by melt forms. Overlying that was our March snowfall, a 4F-4F+ slab of dry snow with a barely noticeable interface between the larger snowfall event from around March 20 and the smaller events around March 23 and 27. Above that lied a series of three melt-freeze crusts to the surface. We got an ECTN 19 about 10 cm down, below the middle of the upper three melt-freeze crusts; the fracture was non-planar and irregular. In our compression test we got a CT 23 about 33 cm down on the interface between March snowfall events, the layer broke on one loading step but did not slide off particularly easily. We also got a CT 29 on the same interface as the one that failed in our ECT with a very similar fracture characteristic. Although we did not examine it as thoroughly, the snow on the north side of Babcock Peak was still very dry, cold, and soft, with more evidence of wind loading. The surface on the south side between 13,000 and 11,000 feet finally began to soften to corn around 1:00 pm. On the exit through southerly, below treeline terrain, the snow was certainly a little softer than in the alpine but still not horribly punchy and we observed no signs of wet avalanche activity.
Avalanche
No new avalanches were observed, but certainly observed the plentiful evidence of the widespread wet loose activity that occured on solar aspects earlier this week in the Boren Creek basin.