Professional Observation
Basic Information
Observation Details
Observation Date:
March 26, 2021 - March 26, 2021Submitted:
March 27, 2021Observer:
WAC - Killian SumpZone or Region:
Southern WallowasLocation:
Norway BasinSigns of Unstable Snow
Recent Avalanches?
YesCracking?
IsolatedCollapsing?
None ExperiencedSnow Stability
Stability Rating:
FairConfidence in Rating:
ModerateStability Trend:
ImprovingBottom Line
On March 26 at 12:15pm, observed a skier triggered wind slab at 8,700 ft on a NNE aspect. The skier (observer) triggered the wind slab on a ESE portion of the gully, a loaded micro-aspect on the NNE couloir. The 8 inch crown broke above skier, pushing them into the gut of the chute, where the debris entrained more snow as it carried though the slot, victim took a 1,000 ft ride. Victim was not buried, and sustained a shoulder dislocation. The day before had seen 4 inches of new snow and the night prior, winds from the NW in the teens. A humbling reminder of how little wind and new snow it actually takes to load micro aspects in the alpine with reactive wind slabs.
Media
Advanced Information
Weather Summary
Cloud Cover:
Partly CloudyTemperature:
31Wind:
Light , NWWednesday night and Thursday brought us 4 inches of new light snow. Thursday night we saw moderate winds from the NW. On Friday, N aspects appeared cross loaded, scoured in places, with some obvious loading on S aspects.
Avalanche Observations
| # | Date | Location | Size | Type | Bed Sfc | Depth | Trigger | Comments | Photo |
|---|---|---|---|---|---|---|---|---|---|
| 1 | Past 24 hours |
The Horn (Granite Mtn) NE 8,700 |
D2 | WS | O-Old Snow | 8 in |
AS-Skier u-Unintentional |
Skier was caught but not buried. Minor injury sustained. |
|
D2 wind slab with an 8 in crown, broke on a solar aspect within a NNE facing couloir, entraining the rest of the snow in the chute on its way down its 1,200 ft path length. Debris was approx. 125 ft wide in apron.
Avalanche Problems
| Problem | Location | Distribution | Sensitivity | Size | Comments |
|---|---|---|---|---|---|
Wind Slab
|
|
Layer Depth/Date: 4-12 in |
|||
Wet Loose
|
|
Layer Depth/Date: - |
Wind slabs are tricky - look out for smooth looking snow, punchy surfaces, or obviously wind-affected pockets. Think twice about skiing consequential terrain when wind drifted snow is present.
Terrain Use
We chose to step out into a steep chute on an aspect that seemed protected or at least wind-buffed instead of loaded. Didn't consider the ESE mirco-aspect within the ENE facing shot. This micro-aspect (sidewall) had been saturated by a sun affect, and there was a more distinct crust underneath the shallow slab here. Wind slabs can be tricky and everyone involved learned a good lesson in terrain management.
Close