Got a large rolling whumpf while skinning on the well established main skin track on Eddies at 1800’ on our third lap around 2:40. Impression of the area that whumpfed (collapsed) was 20’x20’ up hill of us (group of four closely spaced).
We dug a pit to see what the weak layer was. Total snow depth ~145 cm. Top ~50 cm fist hard new snow. ~95 to ~ 36 cm four finger hard slab. 1 cm facets on top of thanksgiving rain crust at 35 cm. Below the rain crust there was 10 cm of loose sugary fist hard facets to 15 cm of four finger hard facets on top of 10 cm of one finger hard pack snow. We believe the collapse was on the 10 cm of sugary facets below the thanksgiving rain crust.
On our first lap I skinned off the main skin track in that area to feel the snow and try to get collapses and did not find anything of concern.
By the time we had the whumpf lots of people had skinned up and at least one group had skied down in that area.