Pro Field Report
Basic Information
Observation Details
Observation Date:
January 23, 2023Submitted:
January 23, 2023Observer:
SAC - Chris LundyZone or Region:
Banner SummitLocation:
Cape Horn (6700-8800', primarily NE-E)Signs of Unstable Snow
Recent Avalanches?
None ObservedCracking?
None ExperiencedCollapsing?
None ExperiencedSnow Stability
Stability Rating:
GoodConfidence in Rating:
ModerateStability Trend:
ImprovingBottom Line
I found the primary weak layer of concern to be the surface hoar layer that was buried in early-January and is now 1.5-2' deep. I only found this layer in one snowpit, and it was showing signs of improvement. However, the variable and sporadic nature of surface hoar - and a somewhat recent skier triggered slide that I observed today - continues to give pause.
Advanced Information
Weather Summary
Cloud Cover:
OvercastWind:
Light , NTemps felt colder than weather stations indicated - I would have guessed mid teens. Ridgetop winds were on the upper end of light gusting to moderate. Little snow being moved, and only small amounts remain available.
Avalanche Observations
| # | Date | Location | Size | Type | Bed Sfc | Depth | Trigger | Photos | Details |
|---|---|---|---|---|---|---|---|---|---|
| 1 |
Jan 21, 2023 (+/- 3 days) |
South of Boundary Creek Road N 7250ft |
D2 | SS-Soft Slab | O-Old Snow | 1.5ft |
AS-Skier u-Unintentional |
|
Report |
Snowpack Observations
Primary goal was to look at weak layers in the top 1m of the snowpack, particularly on shady slopes.
I only found the 1/5 SH in 1 of 3 pits. Where I found it was a very sheltered opening at middle elevations (8250, NE) - a place where I often find SH. In this location, the layer was very thin/compressed and most of the SH was in fragments. 2 ECTS: one ECTX, one ECTP with very hard force. Additional layers (likely 12/19 and 12/26) were present 60-90cm subsurface, but these produced no result and wouldn't shear when I tipped the block out.
I did two other pits around 8800', ENE. These were semi-sheltered slopes but fairly representative of upper elevation start zones. I did not find the 1/5 SH in either location - only small, indistinct FC. ECTX even with very hard hits. In one of these pits, I did see an old SH layer down 95cm that produced an ECTP with very hard force. I believe this is likely 12/8 but I couldn't say for sure. The SH xtals were 5-8mm but mostly laid over. Given the lack of reactivity in tests and that the bottom 50cm of the slab was P+ this layer didn't seem that concerning.
HS in these locations was 170-190cm.
Avalanche Problems
| Problem | Location | Distribution | Sensitivity | Size | Comments |
|---|---|---|---|---|---|
Persistent Slab
|
|
Layer Depth/Date: 50 Weak Layer(s): Jan 5, 2023 (SH) Comments: Rose shaded where observed. Layer was unreactive in tests but I'm calling it stubborn due to semi-recent triggered avalanche. |
I only found small drifts from the recent N winds and these produced only minor cracking, although I wasn't in the best terrain for assessing wind slabs. I would anticipate there being a minor wind slab problem in the right terrain.
Terrain Use
I avoided avalanche terrain due to solo travel