Vail & Summit County
SnowpackAndrew McWilliams · Mar 26, 2024 · Vail & Summit County
Weather
There was light snowfall with about an inch of accumulation while I was in the field—temperatures in the teens and moderate winds from the northwest.
Snowpack
Where I traveled on northerly-facing slopes near and below treeline, the height of snow doubled since the last time I was here in early February. Near treeline close to the ridgetop, I found about two meters or more of snow and the early February (2/2) weak layer is buried over a meter deep. Most of that snow is from upsloping storms in March. While the 2/2 weak layer is deep, rounding, and unreactive in snowpit tests, there was a new layer of faceted grains just below the most recent snow. These near-surface facets are about 20-30cm deep and were formed during the dry spell between the last upsloping storm and the most recent snow. Where I dug, there was no slab above this weak snow, however moderate winds were drifting and stiffening the most recent snow while I was in the field. In an Extended Column Test (ECT), I got a non-propagating result after 5 taps from the wrist on this layer. Nearby, where the slope was more exposed to wind and faced more northeast, I triggered a small Wind Slab avalanche that broke within the newest snow. If drifting continues, I would be concerned about avalanches breaking a little deeper, on the newest faceted layer. I did not get to investigate east-facing slopes, but my guess is that this newest weak layer is confined to sheltered, northerly-facing slopes. Westerly-facing slopes at upper elevations still have a cohesive slab from the March upslopes. The coverage on this slope was still unusually good for this ridgeline. Where I dug, there was about 10 to 20cm of new snow on the March slab (about 30 to 40cm thick) resting on 5 to 10cm of basal facets, but the height of snow was variable on this slope and I bet the slab varies in thickness too. There was a thin and breakable crust formed between the most recent storms at about 12,000 feet. Just a few hundred vertical feet lower, this crust was about two inches thick and was supportable to ski travel. I got a propagating result in an ECT after multiple blows from the shoulder at the interface with the basal facets and the recent slab. Given the coverage, I'd still be concerned about triggering an avalanche were this cohesive slab rests on a thicker, more continuous layer of basal facets.