Yesterday’s “in your face” avalanche activity presents a very clear pattern – all the north, northeasterly and northwesterly facing slopes, above about 9500’ are suspect. Most have a layer of weak, sugary old snow from October on the ground, and if the slope hasn’t slid yet, it could. Slides will be 2 to 4 feet deep, can be triggered remotely from a distance and from below, or by the third person on a slope, and will take out the entire snowpack to the ground. Widespread collapsing, or whumphing noises, are a huge warning sign that you are in an area with this old snow weak layer.
Recent Activity
The weak facets on the ground were active as expected yesterday, but I didn’t expect the shallow layer to be able to connect across terrain features as wide as the huge remotely triggered slide on north facing Sunset – a ¼ mile wide (10,400’, upper Big Cottonwood). There were 4 other slides breaking to the ground on the facets, 3 remotely triggered, with a person carried in 4th. They were 60’ to 100’ wide, all on northerly facing slopes, at 9700’ and above. (Upper Days, Patsy Marly, Sunset/Rocky point. Check out the details in “All The Good Stuff” ). Explosive control work at the Little Cottonwood resorts produced similar results of large avalanches breaking near the ground.
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