Northern San Juan
AvalancheColin Mitchell · Dec 27, 2022 · Southern San Juan
Weather
Overcast skies with unseasonably warm temperatures, and calm winds at pass level.
Snowpack
The structure in the northeast-facing paths on this highway section, the Champion group and West Lime, is largely unchanged since last week. The snowpack in these paths consists of an upper layer 5-15 cm thick, of either Pencil-hard wind slab (West Lime), or 1F- rounds (Champion group), all perched on top of 20-30 cm of Fist-hard depth hoar and large-grained facets. Although coverage is still thin overall (HS of around 45 cm), the structure exists for slab avalanches with the addition of a large load. The more southerly-facing paths, like East Lime and Henry Brown, are down to 3-6" of isothermal, wet, melt forms, and coverage is getting spotty. Trees, rocks, and downed timber are starting to melt out. The Engineers are holding up a little better, with 40-60 cm of snow in the bottom two thirds of the paths. The steep upper start zones have received more solar input, and are thinner. Structure here is better than in the more northerly-facing paths, but not great. Faceting has weakened the snowpack top to bottom. Structure can be generalized as a 10-15 cm thick P- old wind slab over 30-40 cm of 4F mixed forms. A big load could create some problems here.
Avalanche
No new activity observed today.