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Location (general area)
Road conditions to area
Broken clouds (4/8 but not all)
Light (1-16mph Flags/twigs in motion)
Wind direction in degrees
Aspect in degrees
Boot/ Ski penetration
Activity, recent avalanches
Whumping, shooting cracks, collapsing. Q1 releases. 3 bad layers. Not good.
Whumphing noises, shooting cracks. collapsing
Obvious avalanche path
Today I was teaching mountaineering and was leading a group up a small protected slope when the 30 degree slope whumped and I had several cracks surrounding me. I decided it was a good time to go get the pit kit.
Executive summary: Aspect: East. 8000 feet. Observed whumping and cracks. Dug three ECT pits. Three troublesome layers, one about an inch down (easily fails in shear ECT 0-4), another about 4-5 inches down (this is the one that whumps and easily fails in compression ECT 14) consisting of completely saturated 2mm grains. Final troublesome layer is ground level depth hoar. Bottom layer propagated only when I gently pried the block with my shovel. It did not fail after ECT 30, but had a Q1 release when I pried with the shovel so I suspect the mass of the wet snow isolates this weak layer.
Layer 1: 1-5 cm deep. Fully wetted 2mm grains. 1” thick. 4f hardness. -1C. Failed spontaneously while digging 2 of 3 pits today. Upon first or second blow water saturated crystals shot out of the test block 1/3 way across ECT test slab. Several times this layer popped out two feet in front of me while walking.
Layer 2: 5-15 cm deep. Fully wetted 2mm grains. 1” thick. 2-4f hardness. -1C. Failed on second elbow blow but did not propagate across ECT test block. This is the layer that repeatedly whumped .5 meters around me.
Layer 3: Saturated ground level depth hoar. Didn’t fail @ ECT30 but failed with a Q1 fracture with only light prying.
My thoughts: Whumping and cracks are bad. Q1 propagation, regardless of the cause, is bad. So while none of the layers propagated across the ECT test, I’m still going to rate the stability as suspect based on the whumping and cracking. When the snowpack cools down Layer 1 looks likely to sinter and become an ice layer. Layer 2 is too airy to be able to gain enough strength to support additional loading. With sintering this layer may become even more brittle and so will likely be a persistent threat. Layer 3 is also troubling as it is a 1-2” thick layer of depth hoar with no signs of strengthening. Upon any new loading I plan to ski/climb only on areas formerly melted to the ground as any new loading will likely present significant slab avi potential over layers 2 and 3.
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