Pro Field Report
Basic Information
Observation Details
Observation Date:
January 7, 2020Submitted:
January 7, 2020Observer:
SAC - Davis, JostZone or Region:
Banner SummitLocation:
Copper MountainSigns of Unstable Snow
Recent Avalanches?
YesCracking?
None ExperiencedCollapsing?
None ExperiencedSnow Stability
Stability Rating:
GoodConfidence in Rating:
ModerateStability Trend:
SteadyBottom Line
Cut lengths on large column tests still point toward propagation for both the 12/7 surface hoar and the depth hoar/facets/crusts at the base of the snowpack. If the weather forecast verifies, I can't imagine these layers emerging from the other side of this next storm without producing some wide, full depth avalanches.
There is a thin facet layer down 40 cm at 12/31 (ECTN). We only observed one clean shear on this layer as a block fell into our pit. Hand pits along SW-S-SE didn't turn anything up but we also generally lacked much of an overlying slab.
Advanced Information
Weather Summary
Cloud Cover:
Mostly SunnyTemperature:
MildWind:
Moderate , SWPartly cloudy skies increased to mostly cloudy by late afternoon. Plenty of sun throughout the day was making snow sticky on sheltered middle and low elevation slopes. Wind transport of snow was apparent along alpine ridges in the central Sawtooths but much less so in the White Clouds and Boulders. Snow was sifting into skin tracks on Copper but not much efficient transport to speak of.
Avalanche Observations
| # | Date | Location | Size | Type | Bed Sfc | Depth | Trigger | Comments | Photo |
|---|---|---|---|---|---|---|---|---|---|
| 1 |
Headwaters NE 9600 |
D2 | Wind slab along a corniced ridgeline. This was the only fresh slide I noticed. | None |
I did a quick look into the Boulders and southern Sawtooth from Galena Pass. I also had a good look around the Banner area but didn't spend time glassing the Central Sawtooth.
Snowpack Observations
@8500, WSW, HS=100cm:
(12/7) Surface Hoar down 75 cm - ECTX, CPST 36/100 END, PST 25/100 END. Still here, although looking a bit squished into upper and lower slab.
Depth Hoar/Crust/Depth Hoar down 90 cm - ECTP28, CPST 30/100 END, PST 36 and 45/100 END. Failing in depth hoar above a stout (P) crust. https://www.instagram.com/p/B7CZHv1l0x-/
Avalanche Problems
| Problem | Location | Distribution | Sensitivity | Size | Comments |
|---|---|---|---|---|---|
Persistent Slab
|
|
Layer Depth/Date: 50-90 cm Comments: Basal facets and/or depth hoar, often coupled with at least 1 melt-freeze crust. |
|||
|
Persistent Slab
|
|
Layer Depth/Date: 75 cm, (12/7) Comments: Distribution based on previous obs. We found it in our WSW middle ele. pit but not in hand pits on middle ele. SW-S-SE. |
Terrain Use
We avoided avalanche terrain unless shallow and/or lacking a slab.