Southern San Juan
SnowpackChris Bilbrey · Feb 21, 2024 · Southern San Juan
Weather
Mix of overcast, broken, and sunny skies. Moderate southwest wind moving snow above treeline, but not forming fresh slabs.
Snowpack
Digging and traveling across most aspects at upper elevations, the primary layers of concern are the early-February facets. These two interfaces are around 55 to 85 cm deep depending on aspect and slope location, and vary between 4F and 1F-. Where these faceted grains are shallower, snowpack tests continue to produce sudden collapse and resistant planar failures with moderate force. While places where the same layer is closer to 85 cm deep, we observed hard force break failures and ECTNs. Regardless of depth, these grains are showing evidence of rounding edges, but many grains still have angular sides. Probing near steeper rollovers, windward areas near ridgelines, and around exposed rocks and base of cliffs, we could still find places with an atypically shallow slab over weaker snow layers. Additionally, we could easily punch through to weaker snow layers below in most of these more shallower spots. The recent weather regime is promoting extensive near-surface faceting on shady slopes at all elevations around 10 to 20 cm deep (deeper near and above treeline). These grains sit directly above harder snow layers (1F to pencil). Sunny slopes at all elevations have developed a firm crust that becomes slightly more breakable in the near and above treeline elevations. Below these crust (generally 2 to 4 cm thick) are very weak facets. We observed progressive collapse failures with less than 10 taps suggesting this could be a worrisome combination once fresh slabs build above. The January 4 interface is now around 130 and 150 cm deep and was unreactive in multiple snowpits. This interface likely needs a multi-day storm event or spring warmup to return as an avalanche threat.