Sawtooth Avalanche Center

Pro Field Report

Basic Information

Observation Details

Observation Date:
November 23, 2020
Submitted:
November 24, 2020
Observer:
SAC - Chris Lundy (off duty)
Zone or Region:
Banner Summit
Location:
Copper Mountain (6900-8900', W-SW; N at 8800')

Signs of Unstable Snow

Recent Avalanches? 
None Observed
Cracking? 
None Experienced
Collapsing? 
None Experienced

Snow Stability

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

Bottom Line

Snowpack is generally stable and right side up. The important exception is on upper elevation, shady aspects where a layer of depth hoar/large-grained facets from October exist. This layer looks ugly, was reactive in tests, and is buried deep enough to be unpredictable.

Media/Attachments

Snow pit on Copper Mountain, 8800', N. Depth hoar layer near ground yielded ECTP24.
October snow coverage on Copper Mountain the day before the early Nov snowfall began. These areas are where you're more likely to find weak snow near the ground.
Depth hoar layer from October snow on Copper Mountain.
Snow pit on Copper Mountain, 8800', N. Depth hoar layer near ground yielded ECTP24.

Advanced Information

Weather Summary

Cloud Cover:
Overcast
Wind:
Light , W

Observations were from 1300-1630. Clouds increased through this time period, with light snow flurries falling in the late afternoon. Temps remained brisk up high.

Snowpack Observations

Similar to observations from other locations in the forecast area, the snowpack is generally supportable, right-side up, and stable. The melt-freeze crust from the pre 11/17 warm-up and/or 11/17 rain event is present on all aspects and elevations here. Snow near the ground is strong and up to 1F in hardness.

The notable exception is where October snow existed before the early November snowfall (see photo in media). A pit dug on a N aspect at 8800' revealed an ugly weak layer (11/7) near the ground consisting of large-grained facets/depth hoar on a melt-freeze crust 95cm deep (3'+). This layer gave an ECTP24 result. See photos below and in the media section. This is a border-line deep slab problem: likely difficult to trigger, but it would produce a dangerous slide. Time and more observations will tell how widespread this problem is and how long it persists.

Snow surfaces are becoming very faceted and surface hoar exists on many slopes. You could get a loose dry avalanche to go on slopes over 40*.

Snow pit on Copper Mountain, 8800', N. Depth hoar layer near ground yielded ECTP24.
Depth hoar layer from October snow on Copper Mountain.

Avalanche Problems

Problem Location Distribution Sensitivity Size Comments
Persistent Slab
Isolated
Specific
Widespread
Unreactive
Stubborn
Reactive
Touchy
D1
D1.5
D2
D2.5
D3
D3.5
D4
D4.5
D5
Layer Depth/Date: 95cm
Weak Layer(s): Nov 7, 2020 (DH)
Comments: This info is based on limited information.

Terrain Use

After seeing the 11/7 weak layer in the high, north pit - I would not feel comfortable entering consequential avalanche terrain where that layer exists.