Northern San Juan
AvalancheJeff Davis Chris Bilbrey · Jan 2, 2024 · Northern San Juan
Weather
No wind. Abundant sunshine and mild afternoon temperatures. One cloud, maybe two.
Snowpack
Digging on a north-northwest aspect around 12,400 feet, we found a mid-pack structure consisting of hard wind layers and rounding facets. The basal structure here is similar to many other places in the San Juan Mountains - large grain facets and depth hoar near the ground. Snowpack tests produced hard propagating failures in ECTs on the ground, but also highlighted a mid-pack weakness just below the surface slab. Weaker layers closer to the surface are likely to become reactive first with the next meaningful snow load. Overall, the snowpack was supportable to the weight of a human on skis and snowmobiles, but boot penetration was to the ground with little resistance of the mid-pack slab. Southerly-facing slopes offered a hint of softening under direct sunshine. Hard, wind-pressed surfaces offered more challenging travel today than crusted surfaces. We did not observe any cracking or collapsing. Although we are in a period of "Generally Safe Conditions", our snowpack structure is weak but unreactive. This is a different scenario compared to "Generally Safe Conditions" in the springtime when the snowpack is stronger and more setup for the season. With a stormy period forecast over the next week, it's important to remember that all elevations have weak snow in some capacity. Avalanches will become more likely as the new snow stacks up and starts to overload buried weak snow layers increasing potential avalanche size.
Avalanche
Observed a localized, widespread natural avalanche cycle on southerly slopes (SE-S-SW) in this area. Almost all the slides we saw likely ran during the strong wind event at the end of December. While most were small, a few were larger in size.