Vail & Summit County
SnowpackDylan Craaybeek · Dec 20, 2022 · Vail & Summit County
Weather
Beautiful sunny morning with increasing cloud coverage throughout the day (Few to Overcast) with increasing wind (Light by 16:00 at ridgetop) and light snowfall (S-1) by 16:00.
Snowpack
The main story of the snowpack is rapid near-surface faceting (FCsf) in the upper 40cm of the snowpack. This kinetic growth process is weakening any shallow buried slabs decreasing the potential for slab avalanches wherever the slab is less than around 50cm thick so most wind-sheltered areas. West aspects still have a facet-crust combination that showed propagating failures in extended column tests (ECTs) in 10-20 taps but with weak (4F to F hard on the hand hardness scale) snow making up the entirety of the snowpack above the facet-crust combos the potential for slab avalanches is decreasing on this aspect as well. There is widespread surface hoar development around the Vail Mountains backcountry with an average grain size of 5mm but some as large as 14mm in size. The buried rain crust from November 5 can still be found on several slopes, although it seems to be mostly decomposed through faceting in most areas. Although most ECT scores showed fracture initiation without propagation or propagation between 25-30 taps propagation saw tests (PST) showed relatively low scores mostly between 25-35/100. On wind-loaded slopes there is still a dangerous slab over weak layer combination, only the slab is 2 meters thick or thicker and unlikely to be triggered by the weight of a human, however this means the most dangerous places are where the slab is thinner and you can affect the weak layer and trigger an avalanche that propagates far distances. These dangerous areas could be around rock outcrops, trees, or towards the bottom of the slope where the wind-loading is less intense and the slab is thinner. These are also the only areas where I experienced collapses while traveling through the backcountry today.