Southern San Juan
AvalancheChris Bilbrey · Dec 19, 2023 · Southern San Juan
Weather
A sunny start transitioned to grey bird skies. Winds increased along ridgetops midday, but never got strong enough to produce blowing snow.
Snowpack
Basal facets/ depth hoar range, on average, 45 to 60ish cm's below the surface, are large, and seem mostly preserved. Multiple softer near-surface facet layers exist in the upper snowpack. We anticipate they'll wake-up and become more sensitive with the next moderate new snow load. Multiple snowpack tests across various aspects and elevations point to a stubborn slab, weak layer combination. However, the primary weak layers of concern to produce a larger avalanche is still within prime trigger range for a rider or machine - especially where the overlying slab is thinner or total snow depths are less. Despite extensive faceting in the upper portion of the overlying slab, the lower portion (about half) remains in tact with a more cohesive structure/ harder layering. This contributed to supportive over-the-snow travel, but boot penetration is mostly to the ground except on southerly-facing slopes with stout crust/ facet sandwich below. Sunny slopes below treeline are by far the shallowest and least concerning to manage with plenty of down tree skipping. Higher up, those same aspects looked worked over by recent sun and warm temperatures. The varying thickness of surface crust will likely dictate how much of a new snow load they can handle before weaker facets below fail from the added weight.
Avalanche
None observed