Southern San Juan
SnowpackChris Bilbrey · Jan 3, 2023 · Southern San Juan
Weather
Moderate snowfall throughout the day and obscured skies. Daytime accumulations of about 3 inches. Winds were steady out of the southwest forming soft drifts along ridge tops.
Snowpack
We found 9 inches of fairly low-density snowfall over the last 24 hours and deeper amounts up high. Since December 28, the snowpack has gained a lot of depth. More or less continuous snowfall, with micro peaks in intensity, has allowed the snowpack to take its licks. Persistent weak layers that contributed to many avalanches during early December are now buried around a meter up to 150 cm below the surface on northerly and east-facing slopes. The lower layers of the storm snow also appear to have bonded well to buried crust on southerly-facing slopes. Probing on southwest and southeast-facing slopes detected a shallower crust with weaker snow below. Cracking and collapsing were mostly absent on our travels except for cracks at our skis in soft drifts formed by steady southwest winds. Stability tests on north to east-facing slopes yielded dirty, sudden collapse failures at storm density changes and inconclusive results in a buried surface hoar, near-surface facet layer (Resistant Planar in CTs and ECTNs). While this points to stubborn weak layer behavior, large to very large natural avalanche activity at the new year suggests that while it might be harder to impact weaker snow below, sizeable propagation and deep failures are not out of the question at present. Deeper drifted areas, where storm snow interfaces might be more reactive and likely to fail from the weight of a rider, could provoke the cascading effect of triggering a failure deeper in the snowpack. The avalanches we spotted failed near steep, rocky outcrops and in concave terrain features with thick wind-drifted slabs.