Aspen
AvalancheDylan Craaybeek · Dec 30, 2022 · Aspen
Weather
24F and Broken sky in Ashcroft around 11:00. Increasing cloud coverage throughout the day with snow starting around 14:00 and steady S2 with Light wind and Moderate gusts by 15:00 up by American Lake. Atmospheric snow forms falling with a fair amount of rime on a mix of mostly needles with some plates and small (1mm) stellar dendrites.
Snowpack
It won't take a whole lot for the snowpack to reach a tipping point and a natural avalanche cycle to occur with the current snowpack setup. The primary layer of concern is still the mid-November dry-spell facet layer buried 60-90cm deep on north, northeast, and east aspects and as much as twice that on wind-loaded terrain features. There is a combination of basal facets and old decomposed melt freeze crusts that have fully developed into facets on westerly and southeast-facing slopes buried under a slab about 30-50cm deep. To add to the concern a buried layer of surface hoar exists on almost all slopes around this drainage and is currently buried 10-20cm below the snow surface. This could be another layer of failure for avalanches as a slab develops during the next few days of snowfall. No collapses or shooting cracks were experienced until the near treeline elevation band where three slope-wide collapses were triggered on north, east, and southeast-facing slopes. The southeast-facing collapse was on a slope steep enough to slide a couple inches downslope before coming to a stop. All of the collapses were triggered when walking near vegetation where it is easier for the weight of a human to affect the persistent weak layers (PWL) near the bottom of the snowpack. Compression tests all failed on the buried surface hoar layer in less than 5 taps but there is not enough of a slab above this PWL to get propagating results in extended column tests. All extended column tests on aspects highlighted by the Persistent Slab avalanche problem had propagating failures in less than 20 taps when the slab was less than 90cm thick.
Avalanche
Observed one slab avalanche above American Lake that likely slid yesterday. Numerous loose avalanches in the surface snow below cliff bands and trees.