Vail & Summit County
SnowpackAndrew McWilliams · Jan 28, 2025 · Vail & Summit County
Weather
Clear skies with light southerly winds. Below-zero temperatures quickly warmed to the teens.
Snowpack
I purposefully chose snowpit locations on northwest and southwest slopes where there was a slab, but the depth and density of the slab varied significantly as you moved across the slope. In some areas there was no slab, the snowpack was less than a meter deep and was composed entirely of facets. The snowpack was just a deep winddrift in other areas without much layering. You could find all three types of snowpack within a few feet of each other. I easily identified the December Drought interface in both pits. Extended Column Tests (ECTs) yielded either no result or propagating results after blows from the shoulder at this interface. Propagation Saw Tests (PSTs) results to the end of the column after cutting about 40cm into a meter-long block. I was also looking for the new weak layer about a foot below the surface. This layer was easy to find on the southwest-facing slope since it was right below a melt-freeze crust. On the northwest-facing slope, it was difficult to find and I'm not certain I would have identified it if I wasn't looking for it specifically. Like the difference in identifying the layer, the results in ECTs where also very different. On the northwest slope, I got non-propagating results at the interface I believe was buried on January 18. The softness of the slab above and the fact the layer was pretty indistinct on this slope made these results make sense to me. On the southwest-facing slope, I got a propagating result in an ECT after 4 taps from the wrist. The column failed just below a melt-freeze crust which is what helped propagate the failure. My PST in this pit got a result after a cut length of only 25cm but the fracture arrested before it went to the end of the block. This is likely due to the softness and thinness of the slab above it, but it's hard to say for sure. There were ski tracks in the chute on both aspects with no signs of avalanche activity that I could see. I didn't observe any cracking or collapsing during my travels. I did see one very small avalanche at the top of the "S" chute directly below a corniced southwest slope. It appeared to break at the interface where I got my ECT result, but I didn't investigate given the small, isolated nature of the slide. Even though my snowpits showed some concerning structure and snowpit test results, I think these areas aren't likely to be widespread across similar slopes in this area. You might find an isolated spot with the right ingredients and trigger an avalanche, but it seems like other aspects are more likely places - like northeast, east, and southeast. That said, I would still be suspect of steep, cross-loaded westerly-facing start zones. Given the weakness of the snowpack overall, any avalanche will easily gouge down into the snowpack and entrain more snow as it slides, growing larger.