Northern San Juan
AvalancheJeff Davis · Jan 4, 2025 · Northern San Juan
Weather
Overcast skies to start the day, and light snow started to fall around 1 pm picked up as I headed out of the field. Temperatures dropped when it started snowing. Southwest wind was strong and gusty, especially near and above treeline.
Snowpack
Digging near the flank of a recently remote-triggered avalanche on a northwest slope around 11,600 feet, a stiff pencil-hard slab sits on the surface on top of a layer of 2-3 mm facets. Below those facets, another stiff slab persists, likely created by a wind event in early December. Below the buried slab, facets, and depth hoar makeup the bottom half of the snowpack. This avalanche failed in the top hard layer but stepped down in some places, even gouging to the ground on shallower slopes. Compression Tests highlighted the weakness below both stiffer slabs, with a score of CT 21 failing simultaneously on both facet layers and popping off the block. An Extended Column Test did not produce results, and my shovel barely made a mark on the surface after 30 taps. This slope was generally a big drifted floating (meaning lots of wind-stripped slopes around it) hard slab.
Avalanche
This avalanche was triggered from a treed area 3 to 4 hundred feet away. It started on a steep northwest slope but pulled snow from west—and southwest-facing slopes as debris moved down a gully. Large, hard snow blocks were observed near trees, with piles over 6 feet deep. The avalanche ran around 350 feet and was 100 feet wide at its widest. The avalanche crown was one to two feet deep, and where the snowpack was shallow, it gouged to the ground. Avalanche reported here- https://avalanche.state.co.us/report/83c8771b-9e4d-441e-bd0e-e4c02e39bdb8