Pro Field Report
Basic Information
Observation Details
Observation Date:
January 18, 2021Submitted:
January 19, 2021Observer:
SAC - VandenBosZone or Region:
Banner SummitLocation:
Langer Peak (6,500-9,000')Signs of Unstable Snow
Recent Avalanches?
None ObservedCracking?
None ExperiencedCollapsing?
None ExperiencedSnow Stability
Stability Rating:
FairConfidence in Rating:
Stability Trend:
Bottom Line
Weak snow from December is buried 3.5+ feet deep in this zone, but weak layer is still producing unstable results. Facets are very slowly healing, but combination of terrible structure (strong snow over weak snow), unstable snowpack tests, and large recent avalanches is enough to keep me out of consequential avalanche terrain in this zone.
Advanced Information
Weather Summary
Cloud Cover:
Mostly CloudyWind:
Light , NBroken to overcast skies, very light precip falling occasionally with no accumulation. Light to moderate winds blowing out of the north, not transporting snow.
Avalanche Observations
| # | Date | Location | Size | Type | Bed Sfc | Depth | Trigger | Photos | Details |
|---|---|---|---|---|---|---|---|---|---|
| 1 |
Jan 13, 2021 (+/- 1 day) |
Langer Peak NE ft |
D2 | O-Old Snow | N-Natural | Report | |||
| 1 |
Jan 13, 2021 (+/- 1 day) |
Ruffneck Peak N 9200ft |
D3 | O-Old Snow | N-Natural |
|
Report |
Observed evidence of several avalanches that failed on deeply buried weak layers during last weeks storm. I was unable to determine what layer these failed on due to the amount of snowfall and wind loading that occurred after the avalanches happened.
Snowpack Observations
Slab over 12/11 is 1m thick in this area, with the majority of the slab being 1F to P. 12/11 facets/depth hoar are showing signs of improvement, but this is happening quite slowly. Where I dug (E at 7,600' HS=130-140cm) the facets were 4F- at the top of the interval and quickly graded to 4F. Density differential between slab and weak layer is still striking. I was unable to initiate fractures at this interface in standard loading steps with an ECT, continued bashing on the column produced fractures that did not propagate. However, PST and CPST produced repeated short cut lengths and propagation to end. CPST 29 and 30/120 END, PST 28 and 35/120 END, all down 100cm on 12/11 interface.
Avalanche Problems
| Problem | Location | Distribution | Sensitivity | Size | Comments |
|---|---|---|---|---|---|
Deep Persistent Slab
|
|
Weak Layer(s):
Dec 11, 2020 (FCsf)
Comments: Location rose reflects where problem is suspected to be at its worst, but the weak snow from December is widespread. Sensitivity between stubborn and unreactive |
Terrain Use
Avoided avalanche terrain. Would have felt comfortable in simple, small avalanche terrain in the low 30s.