Northern San Juan
AvalancheAnn Mellick Jeff Davis · Jan 2, 2019 · Northern San Juan
Weather
Cold, clear, calm. NNE winds picked up later in the afternoon--> banners off high peaks.
Snowpack
Snowfall beginning on New Year's eve left another layer on our building snowpack. Storm totals in the vicinity only added up to 7" (already settled into just 5"). New snow fell on a largely cohesionless snowpack on shady aspects below treeline and did nothing to add strength. Near treeline, the snowpack is a patchwork: some areas harbor very weak, faceted-top-to-bottom trap-door snow while other areas hold a stout midpack that sits on a basal weak layer with soft new snow on top. We experienced some cracking and collapsing where we found areas of stiffer slabs near treeline. We imagine the slabby structure is more widespread and contiguous above treeline, thus one would be more likely to trigger a slide there.
Avalanche
A small natural avalanche cycle occurred towards the end of the New Year's storm- mainly NEerly aspects above treeline.