Vail & Summit County
SnowpackAndrew McWilliams · Mar 13, 2024 · Vail & Summit County
Weather
Light snowfall became heavy as I left the field. Winds were light from the east and temperatures were in the 20s.
Snowpack
The recent avalanche in the Summit path near the top of Loveland Pass likely ran on a weak layer buried in early February. Where I investigated the crown, the slope faced east at 12,300 feet in elevation. The bed surface of the avalanche was about 50cm from the surface. The avalanche broke on a layer of facets resting on a decomposing melt-freeze crust. An Extended Column Test (ECT) had a propagating result on this layer after eight taps from the elbow. A Propagation Saw Test had a result to the end after a cut length of 40cm into a 105cm block. The blocks slid easily off the bed surface into the pit in both tests. In a pit on a southeast-facing slope at about 11,800 feet, free water had percolated through the upper snowpack down to the slab formed in January. In this pit, the early February weak layer was present, but an ECT only had a non-propagating result after taps from the elbow. The pit location was near the bottom of a larger slope, far from the ridgeline. I wonder if water has moved as far into the snowpack at similar elevations closer to the ridgeline where there is more effect from the wind and drifting snow. There was about one to two inches of recent snow on the surface. This low-density snow was resting on crusts of varying supportability that were about 5cm thick. Shaded northerly slopes didn't have a crust, even at lower elevations. High-elevation, east-facing slopes also lacked a recent crust layer. Otherwise, this crust from recent warm, sunny weather was noted on every slope. With the incoming storm, it seems like new snow instabilities and avalanches breaking at the early February weak layer will be the primary concerns.