Vail & Summit County
AvalancheJason Konigsberg · Feb 24, 2024 · Vail & Summit County
Snowpack
The slab of snow making up the upper snowpack and composed of snow that fell in February is cohesive and up to one-finger hard on the hand hardness scale. This slab is 45 to 60 cm thick and rests on a weak layer of four-finger hard, 1 to 2 mm faceted crystals that are strengthening, but still capable of producing avalanches. I dug near the upper flank of the avalanche and got non-propagating results in tests on this weak layer. The snow depth near the upper, northwest-facing flank was the deepest I found in the start zone at 130 cm. Snow depth at the northwest-facing portion of the crown was 107 cm. The February slab was 42 cm thick over the same weak layer mentioned above. At the west-facing portion of the crown, the snow depth was 64 cm. There was a recently drifted slab over a combination of crusts and very weak snow to the ground.
Avalanche
The avalanche broke on different weak layers depending on aspect. On the northwest-facing portion of the slope, the avalanche broke on 1 to 2 mm faceted crystals that were buried on February 2. The avalanche did not step down in some of these areas. In the middle and lookers left portion of the avalanche (west-facing slopes), the avalanche broke on basal facets near the ground and/or a melt-freeze crust that capped these basal facets. In places where it did not initially break at the ground, it gouged to the ground in shallow portions of the start zone. As the avalanche ran, it mostly entrained snow from the start zone and new snow in the track. For the most part, it did not gouge down to older snow in the track or the steep side walls of the gully. There were thin crowns on the side walls of the gully. The avalanche ran 2000 vertical feet and took out very small trees in the path. I observed some large blocks of snow up to 3 feet in height in the track.