Pro Field Report
Basic Information
Observation Details
Observation Date:
December 5, 2022Submitted:
December 5, 2022Observer:
SAC - Chris & Sara LundyZone or Region:
Banner SummitLocation:
Cape Horn (6700-8800', N-E-S)Signs of Unstable Snow
Recent Avalanches?
YesCracking?
IsolatedCollapsing?
WidespreadSnow Stability
Stability Rating:
PoorConfidence in Rating:
HighStability Trend:
SteadyMedia/Attachments
Advanced Information
Weather Summary
Cloud Cover:
ObscuredWind:
Light , SWNew/Recent Snowfall:
~20cm from past 24hrsWind occasionally gusted to M but there was little snow being transported.
Avalanche Observations
| # | Date | Location | Size | Type | Bed Sfc | Depth | Trigger | Photos | Details |
|---|---|---|---|---|---|---|---|---|---|
| 1 |
Dec 5, 2022 (Exact) |
Cape Horn NE 8700ft |
D2 | SS-Soft Slab | O-Old Snow | 3ft |
AS-Skier r-Remote |
|
Report
Link |
| 1 |
Dec 2, 2022 (+/- 1 day) |
Cape Horn E 8750ft |
D2 | SS-Soft Slab | O-Old Snow | 3ft | N-Natural |
|
Report |
Visibility was poor - I wouldn't have been able to see avalanche activity on the drive or across the highway on the north side of Copper.
Snowpack Observations
Slab was thicker and meatier than what is being observed on Galena Summit and south. Starting at 6700', the slab was ~60cm thick and 4F at the base. This increased to an 85cm thick slab that is 1F at the base at upper elevations. Overall HS ranged from 100-150cm.
The 11/27 weak layer presented as: ~30cm of F FC at lower elevations (thick layer of basal FC), a 3cm thick MFcr atop 20-30cm of F FC on mid elevation solars, to a fairly thin layer of F FC atop 40cm of 4F rounding/moist FC (October snow) at upper elevations. We received collapsing on all aspects we traveled on, but the structure and collapsing was most widespread on shady slopes.
A two person simul-stomp on a low-angle ridge triggered a D2 avalanche on the steep slope below. This was a fairly small slope, but the avalanche broke nearly 3' deep the full width of the slope - see avavalanche occurrence report.
A snowpit @8800', E, above a few day old slide looked very similar to the crown profile of the triggered slide. I had ECTX x2 which was surprising, but the pit location likely collapsed at the same time as the avalanche below the site.
Avalanche Problems
| Problem | Location | Distribution | Sensitivity | Size | Comments |
|---|---|---|---|---|---|
Persistent Slab
|
|
Layer Depth/Date: 60-85 Weak Layer(s): Nov 27, 2022 (FC) Comments: Triggered avalanche, widespread collapsing |
Terrain Use
We avoided avalanche terrian