Rapid wind loading. Smooth pillows.
Observation: Turnagain
Location: Bertha Creek
On Saturday, January 23rd, we started our tour from the Corn Biscuit parking lot, then ascended Bertha Creek. Route plan was to be based on snowpack and weather observations. Upon entering the valley, it became clear that strong easterly winds were loading S/W terrain. We skied NNE facing chutes in Bertha Creek and a SSW facing chute into Spokane Creek.
Observer Comments
Weather
Periodic gusty easterly winds. Snow showers. Occasional sun.
Snow surface
Wind affect of variable depth from zipper crust to slabs whose thickness was a function of deposition location.
Snowpack
We dug two pits on a NNE aspect at about 2,800 feet with similar results. With our plan to avoid areas of intense wind loading, these pits were located in an area that was not heavily loaded. Given this plan, I was particularly interested in the stability of the BSH from approximately 1/14, I've been out of town, so I could be wrong on that date. Our ECT failed under the shovel at 19 at the bottom of the storm snow about 10 cms down. It did not propagate across the rest of the column, nor was the failure clean. We continued until 30 with no further results. 5 hard blows produced clean failure 30 cm below the surface on the BSH. The BSH which was clearly visible upon inspection.
A large obvious wind pillow was visible as we dropped SSW into Spokane Creek. We skied around this and it stayed in place.
On one line dropping NNE into Bertha Creek, I ski cut a large extremely steep wind pillow and was surprised to not produce results. On another NNE line in Bertha Creek we stopped 200 vertical feet below the pass due to the development of a new wind slab. This slab was clearly thickening as we approached top, and was 12 cm deep at that point. It was cracking and cleaning sheering though not propagating.
Great skiing!
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