Unreactive buried surface hoar on Lincoln Ridge

We toured on Lincoln Ridge today to look at the Jan 18 buried surface hoar (SH) layer. Moving away from the parking area, we quickly began to find the buried SH layer within the top 1 foot of the snowpack. We continued to find this layer all the way up to the ridgetop. In each of our handpits we noted that the layer was not particularly weak and did not shear easily.

Large SH (10 to 15 mm) that formed last night was present on the snow surface in wind protected areas. It will invariably be destroyed and reformed before the next snowfall.The SH on the surface today was notable in that last night was quite windy and SH usually forms overnight during calm winds.

As we ascended closer to the ridgetop, we began to see signs of recent E wind scouring on the snow surface. We saw the debris of a wide propagating avalanche in the usual wind slab area underneath the large cornices along the ridgetop (NNE aspect, near treeline terrain). The crown had been almost entirely scoured away by the E winds.The remaining blocks of debris suggested that the slab had been 1 foot thick or less.

We dug a pit adjacent to the flank of this avalanche and identified the Jan 18 buried SH layer a little less than 1 foot below the snow surface. This layer did not fail easily, produced rough (BRK) shear planes, and showed unlikely to propagate in snowpit tests. This matched well with the handpit observations.