Vail & Summit County
SnowpackJason Konigsberg · Dec 31, 2024 · Vail & Summit County
Weather
The peaks to the west were covered in fast-moving clouds from the northwest most of the day. Winds continued to drift snow, though I am sure much less effectively than the previous 24 hours. Regardless, the ridgetop loading continues.
Snowpack
It's a simple and dangerous snowpack with a maritime-like slab over continental-like snowpack weak layers. I got constant collapsing on east-facing slopes and found a progressively harder slab with depth. The slab was 60 to 70 cm thick over fist-hard facets that were buried in early December. Extended column tests are showing moderate propagating results. The total depth of the snowpack is around 115 cm with drifted slopes over 150 cm. It's important to note that the drifting is consistent across the slope with the very effective loading. It's not like you probe 150 cm in one spot and find much shallower snow a few feet over as it once was. Slopes are evenly drifted and look fat. For the south-facing slopes I targeted, I found a concerning structure and also got moderate propagating scores below a thin melt-freeze crust ~60 cm deep. The crust was only 1 cm thick. I dug on slopes that were about 25 degrees so it doesn't give me high confidence that the structure is representative of south-facing slopes above 35 degrees. I suspect the crust is thicker on higher-angle slopes and tests would show more stubborn results. The bottom line is south-facing slopes show a structure to conducive to Persistent Slab avalanches. It will be harder to trigger avalanches on these slopes than other more reactive aspects, but it is not out of the picture, especially with continuous loading.