Northern San Juan
AvalancheAmy Pertuz · Dec 18, 2020 · Northern San Juan
Weather
Moderate snow lingered this morning, but skies began to clear mid day. Temps remained in the teens. N and NW winds were seen moving light amounts of snow in the alpine when observation was possible. Snow was not wind affected in the alpine on aspects travelled.
Snowpack
8” of low density snow by mid morning, with more encountered in the alpine, very soft and not wind affected. The layer of interest continues to be the large grained facets at the interface from Dec 11. On many lower elevation aspects, the snow from the last week is roughly half of the snowpack. This layer continuers to be reactive on micro-terrain features, in particular any unsupported or convex terrain. Localized cracking around my skis would occur moments before a rumbling collapse. Easily intentionally triggered as well as remote triggered numerous size 1 persistent slabs failing 30-50cm down on BTL NW and N aspects, sometimes pulling snow off lower-angled terrain. Continued to see small naturals on BTL W aspects. Large rumbling collapses and easy triggering kept me off and out from under any steep slopes today. SE aspect was least reactive as far as widespread whoomphing and remote triggering, but has a spooky facet crust combo down 45 cm that produced propagating results on an ECT.
Avalanche
I spoke to a party who had triggered a handful of slides in the Midnight area on Red 2, NE aspect NTL and BTL. ~D2 Crowns visible on both the ATL NE face (trigger?) and the BTL pitch (ski triggered) visible from Corkscrew gulch. I could see from the highway that the convex NTL rollers in Commodore, NE aspect, had all slid. Unknown trigger. A larger presumed natural ATL NE aspect was visible up above Mill Creek, near the Columbine Lake trail. Two smaller slides could be seen near Bighorn Gulch in US Basin, W aspect NTL, unknown trigger.