Southern San Juan
SnowpackChris Bilbrey · Jan 10, 2024 · Southern San Juan
Weather
Cold and windy to start with light snow (S-1). Around an inch of new snow fell overnight. Clouds broke around 8 AM and gave way to sunny skies the rest of the morning. Westerly wind decreased, but remained moderate above treeline. Single digit temperatures warmed into the upper teens by midday.
Snowpack
Snow depths ranged 60 cm below 11,000 feet to around 90 cm near treeline. Snowfall since January 4 has settled into a more cohesive slab and sits above very weak faceted snow that developed during the New Year dry spell. The two slopes we decided to dig on both collapsed as we walked out onto them with long-running cracks around 30 to 50 feet in front and above us. We observed propagating failures (ECTP 8 and 11) failing in the weak facets around a foot or so below the surface. In our near treeline pit, we also observed a propagating failure (ECTP 2) below a shallow, soft wind layer on the surface. Snowpack tests today produced the most reactive results we've observed in some time. Digging deeper, the snowpack consists of larger grain facets of varying hardness. This is a classic San Juan setup where shallower slides have growing potential to provoke deeper ones with such a weak underlying foundation - especially with more snow and wind in the forecast. Like many places across the San Juan Mountains, strong winds over the last couple weeks has done an efficient job redistributing snow above treeline - smooth, filled-in looking slopes adjacent to wind-scoured spots. Around 12,000 feet, we found a hard, stubborn wind-layer on east to south-facing slopes.