Date of Observation: 01/12/2022
Name: Evan Ross & Zach Guy
Zone: Northwest Mountains
Route Description: We started low at Slate River TH, but mainly traveled in the upper Yule Creek area between 12,800 and 10,800 on W to N to E aspects.
Observed avalanche activity: Yes
Avalanches: No new avalanche activity. A few more old avalanches that have not been documented. With closer inspection, we decided that the previously documented avalanche that spanned between Purple and the Blob was another D4 from the holiday cycle. Just another impressive avalanche from that cycle.
Weather: Thin clouds creating partly cloudy sky. Steady moderate winds in the alpine, primarily from the W-NW in the morning and more NE in the late afternoon.
Snowpack: In the alpine, the wind was transporting snow throughout the day. However those winds were creating more variably snow surfaces and wind effect, then they were actually creating new wind slabs. In those same areas, we were also managing old hard slabs that have been created over the last couple of days by recent winds. These slabs were hard, only a few inches thick, and stubborn, but ready to take you off your feet in terrain that you wanted to stay on your feet.
Between Purple and the Ant, there are few places that the snowpack wasn’t altered by the holiday avalanche cycle. We did travel in steep terrain on slopes that didn’t appear to have previously avalanches, but most of the terrain traveled had previously avalanched or had old avalanche debris, all of which has been covered back up by new snow in January. West and Northwest aspects held more trigger-points or areas that the snowpack would go from shallow to deep abruptly. Surprisingly we made some of our best turns on a steep NW aspect starting below about 12,600ft and just below all the windblown snow surfaces near the ridgeline.
All in all for the deep persistent slab avalanche problem we chose to reduce our risk by managing trigger points vs slope angles.
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West face of Agusta
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Anthracite and the Ant
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Given the few trees below the Purple to Blob avalanche, they are not the best way to measure avalanche size. The volume of snow and acres covered are better…
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Crown and estimated runout of Blob
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Ant crown
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Blob crown
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Estimated runout below the Ant. This path ran during the historic cycle of 2019 as well. Because of that, it only knocked over a few mature trees this time