Southern San Juan
AvalancheChris Bilbrey · Apr 22, 2024 · Southern San Juan
Weather
HOT day in the mountains. Sunny skies to start transitioned to broken, cumulus cloud cover taking the solar edge off. Steady winds around 12,000 feet and higher was a nice natural AC.
Snowpack
We dug a couple of snowpits to see how weak and prone the upper snowpack is to rider failure. Our first pit was on a southeast aspect around 11,600 feet. We found 8 to 10 inches of 4F- wet clusters ranging 3 to 5 mm. These easily crumbled below the shovel when performing snowpack tests. Around 2 feet below the surface, we observed sudden planar results in weak, wet grains below a crust with water pooling at the crust interface. Our second pit was on a northeast aspect around 11,900 feet. Height of snow here was 140 cm, and snow grains were moist to the ground. The top 6 to 8 inches consisted of wet, clustered grains. We found a thin layer of water pooling in the middle of the main slab body. Slab hardness here ranged P- to P top to bottom. The bottom 40 cm of the snowpack is 1F- moist Depth Hoar grains. Despite a weaker basal structure, it seems like a lot of water is needed to soften the overlying slab for failure to occur at the ground - a moment that could rear its head come later in the spring. Boot penetration was 8+ inches at lower elevations, but decreased to only 4 or 5 inches above treeline. Probing on alpine slopes, we could easily feel harder layering in the upper snowpack - a benefit from more recent freezing conditions. This has limited wet snow avalanche activity so far during the spring melt.
Avalanche
West aspects continue to be the biggest producer of wet snow avalanches during this season's warm-up. Several older ones, and one newer one - the newer one had less dust in the bed surface compared to adjacent slides. This one also looked more slabbish, but viewed from a long distance.