| Trigger | Skier | Remote Trigger | No |
| Avalanche Type | Unknown | Aspect | West |
| Elevation | unknown | Slope Angle | unknown |
| Crown Depth | unknown | Width | unknown |
| Vertical Run | unknown |
Avalanche: Hatcher Pass
Location: 4068 Obs and Avalanche on Arkose Ridge
APU Snow Science 1 field day, looking for evidence of persistent slab problems. We planned to tour to the ridge of 4068, but found numerous signs of instability and opted to stop and dig pits on the east facing bench at 2750′.
Surprisingly few riders out for a bluebird Friday.
Avalanche Details
Witnessed a large, remote skier triggered slide at 2:35 pm; on the ridge east of the road.
Obvious signs of instability
| Recent Avalanches? | Yes |
| Collapsing (Whumphing)? | Yes |
| Cracking (Shooting cracks)? | Yes |
Observer Comments
Multiple occurrences of shooting cracks and whumphing on slopes steeper than 30 degrees. Cracks were remote in some instances, and propagated tens of meters. Observed several recent avalanches, ranging from small to large on a variety of aspects.
Weather
Sunny and clear skies with calm wind and no precip. Temperature was 28.4F at parking lot, and 23 at our high point of 2750'.
Snow surface
15 cm of soft snow made for enjoyable riding conditions. We did not encounter any wind-affected snow, but saw evidence of wind events near ridgetops. A sun crust was present just below the surface on solar aspects, and sun was softening this snow by our return to the trailhead at 3pm.
Snowpack
We dug 5 west facing pits at 2750'. Snowpack height varied from 110 to 200 cm.
Our layer of concern was 4 cm of facets above a drizzle crust sandwich, around 45 cm down. Stability tests produced several relevant results at this layer:
ECTP11 x2
ECTP13
PST35/100END
PST40/100END
PST45/100END
This layer was unreactive in half of the pits and produced no results.
Notably, the bottom of the snowpack featured 35 cm of advanced facets/depth hoar.
Overall, the snowpack had moderate strength and moderate to high propagation propensity.
Powder cloud from skier triggered avalanche across the valley. Crown visible on peak in center left of image.