Snow tests on Luther Pass

Below about 8100 feet there was a noticeable crust on the snow from previous rain but above that elevation snow was crust free. Above the crust elevation wind was transporting snow (and observable graupel) most of the day. Near and above treeline wind slab and snow cracking was widespread by early evening. 

Before the ECTP (SC) down 57cms on surface hoar video, we had CTM (16) with Sudden Collapse at the same layer. Many compression tests in this area today had Sudden Planar (and a few had Sudden Collapse) but only two pits observed ECTs that fully propogated. Many ECTs would fail at a layer similar to what is shown in the video, and with one additional tap would propagate 15-30cms but not fully across the block (although they would propagate with one or two non-standard additional loading taps). The ECTP was repeatable in this pit location near the pin on the google map.

Two PSTs had 40/100 ARR resuts which seemed to roughly mimic the ECTNs that only propagated partially across the block.

Photo 1: Small buried surface hoar taken from below the slab that failed in the ECT video. It was very difficult to see this surface hoar but once noticed we were able to pick out many buried SH grains. Size was 3mm and it appeared to be mostly lying down. This layer was a mix of decomposing fragmented grains and some small facets along with the surface hoar. 

Photo 2: Surface hoar (not buried) on the snow surface of Grass Lake in the morning.