Pro Field Report

Basic Information

Observation Details

Observation Date:
December 6, 2020
Submitted:
December 7, 2020
Observer:
SAC - VandenBos
Zone or Region:
Banner Summit
Location:
Copper (6,700-9,000', primarily N-NE aspects)

Signs of Unstable Snow

Recent Avalanches? 
Yes
Cracking? 
None Experienced
Collapsing? 
None Experienced
Unsure of timing on potential skier triggered slide on north side of Copper. Likely older than past 48 hours.

Snow Stability

Stability Rating: 
Good
Confidence in Rating: 
Moderate
Stability Trend: 
Steady

Bottom Line

Snowpack continues to weaken, widespread surface hoar growth found up to about 7,500' along drainage. Old snow from October at the base of the snowpack kept me out of terrain holding this snow. This snowpack will not hold up well to a loading event.

Media/Attachments

This photo shows a thin avalanche crown on the northeast side of Copper Mountain in the Banner Summit Zone. It appears to be a wind slab that was created during the spike in wind speeds at the end at the beginning of December. It is unclear if it failed naturally or was triggered by the skier's who left the tracks visible in the photo.

Advanced Information

Weather Summary

Cloud Cover:
Clear
Temperature:
inverted
Wind:
Calm

Afternoon weather obs: Inversion persisting throughout the day. Calm wind. Band of stratus ~20 miles to the west, clear locally.

Avalanche Observations

 #  Date Location Size Type Bed Sfc Depth Trigger Photos Details
1 Dec 3, 2020
(+/- 3 days) 		NE Copper
NE 9000ft 		D1 SS-Soft Slab U-Unknown
This photo shows a thin avalanche crown on the northeast side of Copper Mountain in the Banner Summit Zone. It appears to be a wind slab that was created during the spike in wind speeds at the end at the beginning of December. It is unclear if it failed naturally or was triggered by the skier's who left the tracks visible in the photo.
Report
NE Copper

Snowpack Observations

Intense faceting and SH growth at lower and middle elevations, below the inversion. Less pronounced but still obvious up high. Dug on NE at 7,800' trying to put a lower bound on October snow. HS=80cm. No October snow found here but lower 2-4cm of snowpack trending towards DH, which was moist where I dug. 11/17 presented as 1F crust with facets underneath. Probably some faceting going on above the crust too but less obvious than underneath. 1-2mm SH buried at 11/25 interface, down 7cm. ECTN 5 on 11/25 (down 7cm) and ECTN 17 on 11/17 (down 40cm).

Avalanche Problems

Did not directly encounter avalanche problems. Avoided terrain where October snow was buried at the base of the snowpack. Skiers on NE side of Copper had entered this terrain with no obvious results.

Terrain Use

Avoided terrain where October snow was buried at the base of the snowpack.