Northern San Juan
AvalancheKrista Beyer · Nov 30, 2024 · Northern San Juan
Weather
Cold, clear, and calm. A Rex block off the coast of California appears to be stalling a chance for more moisture for the near-term weather forecast.
Snowpack
Cold weather is weakening the slab characteristics of the snow in all places traveled. In addition, the sensitivity of the Persistent Slab avalanche problem has reduced since the storm. On a northeast-facing slope near treeline I found 37 cm of Fist to Four Finger storm snow sitting above a firm Finger hard wind slab layer 5cm to 1cm thick. This wind slab layer had significant spatial variability over a short distance while moving across the slope. Pit tests and profile are available in media. Moderate and hard non-propagating results failed on a small layer of buried near-surface facets appears to be sitting above the wind slab. While test results are not notable, they point toward a decrease in sensitivity. In addition, they suggest that buried near surface facets are still preserved along with buried wind slabs beneath the new snow. On north slopes below treeline, the new storm snow has lost almost all cohesion, and the entire snowpack continues to facet.
Avalanche
More evidence of an impressive natural cycle was readily available during the tour. Of note, one avalanche propagated wide near treeline into tall timber and released smaller sympathetic slides below treeline. The avalanche ran about 1000 ft, the entire length of the path. Many other avalanches observed in the vicinity that are recorded in separate observations.