Vail & Summit County

Avalanche

Andrew McWilliams · Feb 22, 2023 · Vail & Summit County

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Weather

Snow began about 9am with snowfall rates averaging 1"/hour for the duration of my tour. Winds were strong from the south and southeast with extreme gusts. Temperatures were steady.

Snowpack

Southerly winds were rapidly loading northerly-facing slopes throughout the day near and above treeline. I observed cracking within the new snow that shoot 20 feet from my ski tips. On any steep, loaded slopes, small avalanches running on the interface of the new and old snow were easily triggered. These avalanches were soft and about one foot deep; the drifting snow was low-density and had not formed stiff slabs yet. With a period of southeast winds around noon, these loads will likely be distributed across the northerly side of the compass tomorrow. The activity was limited to the new snow, and no collapses were noted during my travels. Visibility was too poor to get a good look at any avalanche activity in the area, but I didn't notice anything where I traveled. The snowpack where I dug on a north-facing slope near treeline was about 150cm deep with 15cm of new snow and multiple layers of harder, wind-drifted snow alternating with layers of softer, weaker snow for the upper 50cm. The next 50cm was composed of pencil to one-finger hard (on the hand-hardness scale) layers of rounds, facets, and rounding facets. The last 50cm to the ground was depth hoar with a decomposing melt-freeze crust in the middle of the layer. Snowpit test results had easy failures at the interface of the new and old snow about 15cm from the surface. There was a propagating result in an Extended Column Test in a layer of facets about 50cm from the surface, but I could not repeat this result. The forecast calls for continued strong winds overnight and I wouldn't be surprised if the new snow formed stiffer, denser slabs before morning.

Avalanche

I ski-cut a northeast-facing near treeline test slope and triggered a small Wind Slab avalanche that ran on the interface of the new and old snow. 10 feet wide and ran about 100 feet.