Deep Freeze or Microwave?
AvCan Northwest , Tuesday 28th December, 2021 5:00PM
Today we went to the Microwave. We found wind affected alpine conditions and a high temperature of -10C. Winds were moderate from the NE. We could see snow being transported as well as the effects of previous wind transport. We dug at 1800m on a NW facing slope that had been cross-loaded by the wind. We found 40cm of stiff wind slab that failed and produced propagating Extended Column Test (ECT) results with moderate loads. In this area we also found some cracking while walking around (see pics). We also found a layer of facets (weak, poorly bonded snow crystals) 70cm deep that also produced propagating ECT results with heavy loads. On an E facing slope we also found wind slab, however it was 10cm deep here. We did produce failures 10cm deep with moderate loads but did not produce propagating ECT results. We think the likelihood of producing a wind slab avalanche has increased so we avoided skiing and sledding on steep wind-loaded slopes today. The wind slab avalanches could also ‘step down’ (trigger a deeper layer to fail) to the deeper weak layer that we found at 70cm, which would be a high consequence avalanche. We’re going to investigate the distribution of this weak layer over the next few days ahead of the incoming storm...
Snow conditions were: Wind affected. Weather conditions were: Cold, Windy. We rode: Alpine slopes, Mellow slopes. We avoided: Convex slopes, Steep slopes. Riding quality was ok.
Avalache Conditions: Whumpfing or drum-like sounds or shooting cracks.