Spent the past few days on the Duffey at the Wendy Thompson Hut. Conditions continued to improve as time went on, although the vigorous warm storm that smacked the Whistler area did not make it through the blocker into the basin, which was very good news indeed.
On 091220, Cerise was getting patches of rain according to some reports, but these did not penetrate into Marriott above the headwall. Consequently, there was a reasonable amount of lower density storm snow, accumulating to an average 47cm over the two-and-a-half day storm. From 5500ft up, this was right-side up for the most part, and the nearest crust to the surface was normally about 80cm down. Total snowpack in the basin ranged from 240-275cm and everything was quite fully filled-in.
Throughout the majority of the storm, we stayed on low-angled terrain. Compression tests were giving easy results, with occasional failures in the storm snow on cutting the blocks. The interface between the initial cold snow and the rapidly warming second front seemed to be the culprit, and failed regularly in the first couple of taps to a depth of from 32-28cm down.
Facetted grains over the 091128 crust were stiffening up, but still responding with good "pops," usually in the "hard" range. The fact that this layer was down about 74-82cm gave us some concern and we stayed away from any steeper slopes. Overnight on the 21st, temps dropped to -15C and the upper snowpack responded by tightening up noticeably. While still giving sudden planar results on easy compression tests, it was taking significantly more taps to get results.
There was no change in results on the facets above and below the 091130cr however. Extended column tests on the 22nd were all without results. For this reason, we did not test steeper slopes.
It is apparent that a widespread cycle ran through the region mid-week last week when that storm cycle pulled through. Even a few of the glide avalanches on south-facing slopes at about 7000ft. had failed catastrophically. Some loose slides in the latter portions of the storm pulled out slabs to Sz2. With the excellent vis on the 22nd, we were able to see one loose snow avalanche initiated naturally from steep ground that had caused a slab failure lower on the slope during the last hours of the storm on the 21st. In addition, one cornice failure at 7600 had caused a Sz2 when it impacted steep wind-loaded terrain below.
Skiing quality was quite good on the 22nd, with much-improved vis and stability and less ski penetration which made for easier tracksetting.
M. Sulkers
ACMG Hiking Guide
Professional member CAA