Stubborn PWL and New Surface Hoar on Waterhouse Peak

Our AIARE1 class toured up Waterhouse Peak on January 23 to avoid avalanche terrain and observe the Jan 4 persistent weak layer. In our first pit, at about 8400' on a NNE aspect (pin drop location), we observed the Jan 4 crust/facet layer down about 60cm with very little crust. The facets, while large in size, did appear on visual inspection to have rounded. None of our column tests indicated reactivity on the Jan 4 layer, with multiple CTH BRK results and an ECTN, all in a small layer of faceted grains down about 22cm. 

2 other pits at 8650' and 9150' on N and NE aspects gave similar results, with no indication of reactivity on the Jan 4 PWL.

We found small 1-2mm surface hoar in open areas near the trailhead as we started our tour around 10am, and then were surprised, given the warm temperatures, to find large 7-9mm surface hoar near the summit later in the afternoon. (See photos.) We observed this large surface hoar on a NE aspect, even in sunny areas. We noticed, however, that on small pieces of the snow surface that were angled more towards the sun, like edges of old tracks, the same large feathers were present but were lying down flat from melt. 

Winds were calm to light out of the west, and clouds increased from scattered to overcast throughout the day. No precipitation was observed before we left the field around 4:00pm.