Vail & Summit County

Mostly clear skies and light to moderate winds near treeline. Below-zero temperatures rose into the single digits by late afternoon.

We observed a weak and mostly structureless snowpack below treeline about 1 to 2 feet deep. At the upper end of the below treeline elevation band, we dug a quick snowpit on a southeast-facing slope. There were some old crusts in the middle of the snowpack, but these were faceting and losing strength. The snow between them was very soft and weak. The hardest layers were next to the ground and the most recent snow. On east and northeast slopes, the snowpack was worse and nearly unsupportable to skis. On more north-facing and shaded slopes, you could easily push loose snow sluffs on very steep slopes. The most recent snow was about 15 to 20cm, but it was generally soft and did not form a slab. A few hundred vertical feet higher, at treeline, the snowpack was different. Strong winds and some snow last week formed a dense, pencil-hard slab buried by the most recent snow. The most recent snow was also wind-affected, adding weight to the 1 to 2 foot-thick slab. Below these layers was a layer of soft facets resting on a thick crust. The collapse we heard ascending this slope likely failed on this layer, and a recent avalanche below the ridge, another few hundred vertical feet higher, likely ran on this layer too. An Extended Column Test produced a propagating failure after three taps from the elbow in the weak layer. Ascending the ridge to just below the summit of Copper Mountain above treeline, where the slope faced more east, I caused another loud collapse. I was just above a recent avalanche in a rocky chute and ascending untouched snow along the ridgeline. This time, a crack shot a few hundred vertical feet across the slope in front of me. Although the slab didn't avalanche, you could see the crack outlining whole sections of the slab as it traversed the slope. We also got a report of an avalanche in the Iron Mask avalanche path, one drainage to the south.