Northern San Juan
AvalancheAmy Pertuz · Jan 9, 2021 · Northern San Juan
Weather
Milder temperatures today, light winds below tree line, but moderate Westerly ridgetop winds. Very little blowing snow was observed. Increasing high thin sky cover. Another nice day.
Snowpack
A couple of sunny days put crusts on the surface of some sunnier lower elevation slopes. Above tree line, slopes harbor some more variable wind affected snow from earlier in the week, topped with Wednesday’s few inches of new snow. I was able to trigger medium sized collapses on Westerly below tree line slopes where the mid pack slab above the Dec 11 layer was a thicker and more cohesive 1F-hardness layer. In other places, the upper snowpack is mostly 4F hardness, and while easy to moderate failures were occurring at 30cm and 50cm below the surface, the less cohesive midpack slab seems to be too weak to communicate these failures very far, and propagating results were hit or miss in these locations. In areas with this structure, no whumphs or collapsing were observed. Even without a stiffer midpack slab present, the structure still felt too tenuous to tee off on this aspect. Northwest slopes below tree line have less variation of hardness in the upper layers, more consistently 4F+, but also seemed more consistently reactive to skier pressure. Intentionally triggering small test slopes or collapses has become more difficult and more localized on NW slopes near and below tree line, but collapsing and cracking were still observed.
Avalanche
Many repeat offenders noted this week, especially Near and Above Tree line E and NE aspects, including the reported ATL natural near V6/ Mill Creek (NE) and a NTL natural on “almost Paradise” (E) up Ophir Pass rd, both previously ran the 3rd week of December.