| Trigger | Skier | Remote Trigger | No |
| Avalanche Type | Soft Slab | Aspect | Northwest |
| Elevation | 3700ft | Slope Angle | 35deg |
| Crown Depth | 18in | Width | 25ft |
| Vertical Run | 80ft |
Avalanche: Hatcher Pass
Location: Valley of Sin
We went for tour into the Valley of Sin to investigate the persistent slab problem.
Avalanche Details
We triggered a small persistent slab avalanche. This avalanche occurred where an glide avalanche had previously released, and was filled back in with wind drifted snow. This avalanche failed on large depth hoar 6-8mm. This area had snowpack that was much shallower than the surrounding slopes and a low friction bed surface.
Obvious signs of instability
| Recent Avalanches? | Yes |
| Collapsing (Whumphing)? | Yes |
| Cracking (Shooting cracks)? | Yes |
Observer Comments
We had collapsing and cracking at ridge tops during our tour.
Weather
It was cold, clear and calm during our tour day. No new snow was observed.
Snow surface
Snow surfaces were a mixed bag today. Low density surface snow and knife hard wind slab could found in a relatively small distance. Snow surfaces were faceting with the cold weather. Some areas hold soft wind pressed snow.
Snowpack
We dug one pit today. Where we dug we found a old pencil hard wind slab sitting above weak faceted snow. In our tests we had failure beneath an old faceted crust on 3-4mm facets. This location had poor structure, moderate strength, and propagation results. Hand pits and pole probe showed similar structure in some areas during tour today. Distribution of these hard slabs seems to be patchy.
Pk 4068
3100' NW 26°
HS125
ECTP21 failed 60cm from the ground on 3-4mm facets
PST 35/100 END 20211028, on the same layer noted above.
Failed on large chained depth hoar
This avalanche occurred where a glide crack had released earlier in the season.