Southern San Juan
SnowpackChris Bilbrey · Mar 30, 2022 · Southern San Juan
Weather
Mix of sun, clouds, and light snow showers. The wind was efficiently transporting the new snow onto leeward terrain features mostly above treeline. The heater finally turned off and temperatures felt more like winter than spring.
Snowpack
The snowpack as a whole on northerly-facing slopes above treeline remains dry and we found good bonding of storm snow at the new/ old interface. PSa problems in the alpine remain deep, stubborn and we did not find evidence that the new load increased sensitivity on those slopes. Fresh slab formation on easterly slopes at upper elevations posed the biggest threat to triggering an avalanche where we traveled. North and northwest alpine slopes got stripped and wind-pressed from the strong wind. Near treeline, northwest and northeast-facing slopes got moist during the warmup, but layering was consistent below. Less evidence of a moist old snow surface on due north aspects near treeline. East and west aspects felt the brunt of recent warm temperatures with weaker, wet grains below the re-frozen new/ old interface. Below treeline (around 10,800 feet or lower), the snowpack is wet, rotten junk below storm snow on all aspects except due north. A snowpit on a due north aspect at 10,750 feet revealed that melt water has struggled to penetrate through the dense slab formed over the last month. February facets are still dry and rounding, but continue to produce planar failures in tests. While stubborn to trigger, a slide that occurs in the wrong terrain could still break deep. It may take a bit longer for the pack to re-freeze below treeline now that a blanket of new snow caps a generally isothermal snowpack. Wind and cooler temperatures today helped the upper snowpack layers to become more supportive by the afternoon compared to the morning. Its spring-time, and the sun can have dramatic settling effects to the snow surface, and surface warming triggered long-running Loose Wet avalanches in the last 2 days - some triggered dangerous Wet Slab avalanches on west, northwest, and east aspects.