Take this test with a huge grain of salt.
We observed a hollow layer above a crust ~10cm above ground on a convexity with shallow snowpack (~45cm), could reach my whole arm into it. Opted to dig a pit in nearby open area with 100cm snowpack to see if we could find that layer elsewhere.
We did some kind of bastardized extended column test. I got no results, friend tried again on the other side and got an irregular fracture on 15th tap ~25cm down. Result did not propagate to the entire column. Found an indistinct crust at that level. The test was not my finest work but better than nothing.
We proceeded and avoided convexities and terrain traps. Noted variable wind slabs up to ~5 inches on surface. Also noted shooting cracks but they seemed to be limited to the wind slabs.