Sawtooth Avalanche Center

Pro Field Report

Basic Information

Observation Details

Observation Date:
December 31, 2020
Submitted:
December 31, 2020
Observer:
SAC - Ethan Davis
Zone or Region:
Sawtooth and Western Smoky Mtns
Location:
Beaver Creek (Primarily SE-S-SW-W-NW, up to 9,300')

Signs of Unstable Snow

Recent Avalanches? 
Yes
Cracking? 
None Experienced
Collapsing? 
Isolated
One small collapse in flatter terrain near the creek bottom on a S-facing slope.

Snow Stability

Stability Rating: 
Fair
Confidence in Rating: 
Moderate
Stability Trend: 
Improving

Bottom Line

Only a couple of small loose snow avalanches were observed. Possibly a thin slab as well, but very small. The December facets (12/11 layer) are >2' deep and "stronger" here than in the shallower packs I've been in recently (approaching 4F at the base). This layer looked better in the south-facing pit than in the north. If storms deliver next week we may see very large (D3) slides.

Media/Attachments

Loose snow avalanches that likely initiated during the heavier snowfall last night, or during brief bouts of sun today. S-facing, 9,800'
A few generations of small slab and loose snow avalanches from recent storms. E-facing slope at 9,600'.
Very warm temperatures and sunny weather in early December sent melt water from the snow surface down through this layer of facets. As the melting slowed, this column of ice (a "percolation column") froze showing the water's path toward the ground. SSE-facing slope at 8,600'.
https://www.instagram.com/p/CJfDVAVF35R/

Advanced Information

Weather Summary

Cloud Cover:
Partly Cloudy
Wind:
Calm
New/Recent Snowfall:
HST = 15 cm

Very light snowfall throughout the day with little accumulation. Sun popped out here and there but it was never "sunny". Mild temps (mid-20s F)?

Avalanche Problems

Problem Location Distribution Sensitivity Size Comments
Persistent Slab
Isolated
Specific
Widespread
D1
D1.5
D2
D2.5
D3
D3.5
D4
D4.5
D5
Layer Depth/Date: 70 cm
Weak Layer(s): Dec 11, 2020 (FCsf)
Comments: Only one localized collapse on a S-facing slope. Percolation columns and 4F moist snow in S pit. Dry F->4F in WNW pit.

Terrain Use

We stuck to slopes <35 degrees unless they were short and not connected to larger slopes above.