Southern San Juan
SnowpackChris Bilbrey · Mar 26, 2021 · Southern San Juan
Weather
Additional snowfall never materialized today as forecast suggested. Skies varied between broken to scattered and moments of intense sun. No daytime accumulations after around 10 am. Winds were light out of the south. We found 6-10 inches of new snow in the last 24 hours below 10,000 feet and up to 12 inches near treeline.
Snowpack
We observed clear evidence that heavy snowfall in the last 24 hours built cohesive and touchy storm slabs on many slopes at all elevations. This was in the form of small to large natural avalanches and shallow rider-triggered slides on steeper northerly slopes below treeline. We suspect the majority of natural slides were confined to snowfall since 3/21. We noticed stiffer slabs near treeline and avalanches in that elevation band propagated wider in general. Slides below treeline were isolated to steep, open convex slopes. Lots of long-running sluffs out of steep alpine terrain with a few triggering soft slabs while moving down the slope. Stability test in a snowpit on a shallow (115 cm), northeast-facing slope at treeline yielded propagating failures in large facets at the ground. While shallower snowpack areas appear isolated within the La Plata Mountains as a whole, these results suggest that the new snow load has added stress to buried weak snow and warrants evaluation.