Vail & Summit County

Snowpack

Drew Gibson · Jan 22, 2024 · Vail & Summit County

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Observation photo 1Observation photo 2Observation photo 3

Weather

Partly cloudy to overcast with periods of S-1 snowfall. Some quick pulses of S1-S2 snow occurred in the late afternoon but they were 10-20 minutes in duration. Near treeline linds were mostly calm with a southerly light breeze at times.

Snowpack

Widespread rumbling collapses were observed on east and southeast-facing slopes. Steeper slopes (>32 degrees) did not avalanche but slabs moved a few inches. While traveling below treeline it was easy to spot areas that were bare ground before the recent storm as these areas were shallow and had no slab/weak layer combination. On east and southeasterly-facing slopes near treeline the slab was 35cm-45cm thick and was fairly reactive in most places. In multiple test pits, both small and large column tests had failures at 11 taps. Extended Column Tests had almost explosive propagation on the facet layer resting below the slab. See the attached pit and pictures. On more wind-affected slopes the total snow depth was not only deeper (as expected), but the slab was significantly thicker and harder (averaging 60cm and 1 finger hard) The slab is supportive and was difficult to cause a failure in, but I was able to cause collapsing from thin areas on the margin of the slab that communicated into deeper areas. This makes traveling around on the slabs spooky. I could cause a collapse fairly reliably by digging the tail of my ski down into the slab and stomping on it. On northerly terrain near and below treeline the structure is similar to the east and southeast but the snowpack is deeper. The slab is relatively the same thickness, but the weak layers underneath are up 60cm thick. All of the failures I got in test pits were similar to other aspects but since the total depth is more, the potential avalanche size would be bigger. Though I didn't trigger any avalanches, I gave terrain over 30 degrees a wide berth on all aspects. I can't see the possibility of remote triggering a larger avalanche reducing too quickly.