Vail & Summit County
SnowpackAndrew McWilliams · Dec 11, 2023 · Vail & Summit County
Weather
Broken skies and temperatures in the 20s. Winds were light from the west. There were brief moments of snow flurries, but no accumulation.
Snowpack
We observed no cracking or collapsing on the westerly below treeline slopes that we ascended. Once we got to near treeline, we heard many collapses on the west to north-facing slopes we ascended and descended. Most were minor to moderate, but there were some rumbling collapses in flatter, meadow areas. In a snowpit on a west aspect below treeline, we found preserved surface hoar grains below a crust 25cm from the surface. The overlying snow did not have a slab quality and we got non-propagating results in an Extended Column Test after eight taps from the wrist on this layer. Below the surface hoar layer, there was a slab and we got a propagating result at the interface of this slab and the basal facet layer after six taps from the elbow. The height of snow was about 80cm on this slope. We did not find the surface hoar layer buried intact in any other pits; we dug on a south and north aspect. It is likely that on the south aspect it was destroyed by the sun and in the north-facing pit it was destroyed by the wind. This could be a layer of concern moving forward at lower elevations in wind-sheltered areas. In the north-facing pit near treeline, we found two crust layers near the surface. The upper crust was on the surface and was possibly due to warm temperatures and the greenhouse effect with nearly overcast skies. The lower crust was about 5 cm below the surface and looked like a rain crust. It was thin, breakable, and transparent. Neither of these crusts was supportable, but faceting will likely occur between them which could create another problematic weak layer. As we descended the northerly slopes, we could not find these crusts in shaded or lower-elevation areas. The height of snow on northerlies was generally over 80 cm near treeline and the snow was supportable for skiing. There were dense slabs in the middle of the snowpack across the terrain near treeline that became less continuous below treeline although the snow remained supportable. Collapses were less frequent and less loud on below treeline northerlies, but I still observed many.