Vail & Summit County
AvalancheAndrew McWilliams Austin DiVesta · Jan 15, 2025 · Vail & Summit County
Weather
Clear skies and calm winds. Temperatures started in the single digits but warmed to the twenties by the afternoon.
Snowpack
We rode on below treeline slopes and found some good places to dig in leeward terrain features and directly below a steep ridgeline near the summit of Red and White Mountain. The snowpack was generally over a meter. Where we dug on an east-facing slope the snow depth was over 150cm. We observed no signs of instability like cracking or collapsing as we approached our first snowpit location on an east-facing slope. After getting no results in an Extended Column Test (ECT) in our snowpit, I caused a booming collapse as I walked back to my sled. The slab in this area was thick enough and dense enough to be supportable to boot travel. Where we dug on a south and northeast-facing slope, boot penetration was still practically to the ground. Our pit on a low-angle, sheltered south-facing slope had no crust layers and we got a propagating result in an ECT just below a marginally harder layer of facets with the most recent snow on top. While the slab was discontinuous across this slope, where we found it, the structure was concerning. Our pit on a northeast-facing slope directly above the crown of a recent avalanche, also had a propagating ECT result, this time after blows from the shoulder. Interestingly, our result was below the bed surface of the avalanche about 15cm above the ground. A Propagation Saw Test (PST) had a result to end after a cut length of 24cm in a meter-long block at that interface. These results were similar to what we've seen elsewhere in this large zone. ECT results after blows from the shoulder, but short PST cut lengths and no signs of instability. While the slab on shaded slopes is getting weaker, it was still continuous across the slope where we dug today. Overall the snowpack was pretty simple. There is a slab from storms at the end of December that lasted until about January 12 resting on faceted snow from November and October. While both avalanches we saw ran at the interface of the December and November layers, pit results below that level suggest you could trigger even deeper avalanches in some places. In all of our snowpits, we noticed weak snow near and on the surface.
Avalanche
The avalanche we investigated near Red and White Mountain was previously coded in this observation: https://avalanche.state.co.us/report/590c2604-7248-4075-ad65-2632a8ddb584