Sawtooth Avalanche Center

Avalanche Occurrence

View Associated Field Report

General Information

Widespread avalanching in a bowl to the south of Copper Mountain in the Banner Summit zone. This terrain faces NE at 8800'. The crowns are 1.5-2 feet deep. The light is poor, but most of the terrain that was steep enough to slide, slid.

Observer:
SAC Forecaster

Verified by SAC?
Yes

Occurrence Date:
Dec 21, 2020 (+/- 1 day)

Location:
Two bowls south of Copper Mtn, draining into Swamp Creek

Comments:

Numerous avalanches observed, exact count is very uncertain due to mediocre visibility. Essentially anything over 35 degrees ran. Avalanches occurred along the upper elevation ridge crest as well as mid-slope/mid-elevation rollovers. A quick crown profile was completed in one that faced E and broke several hundred feet wide, confirming the 12/11 facets as the failure layer as well as slab depth.

Avalanche Characteristics

# of Avys:
10
Aspect:
NE (NE,E)
Start Zone Elev:
8800ft
Size:
D2
Type:
SS-Soft Slab
Trigger:
N-Natural
Bed Surface:
O-Old Snow
Depth:
1.5ft (max: 2ft)
Weak Layer:
Dec 11, 2020 (FCsf)
Comments:

Avalanche size ranged from D1-2, size generally dictated by scale of terrain.

Media

Widespread avalanching in a bowl to the south of Copper Mountain in the Banner Summit zone. This terrain faces NE at 8800'. The crowns are 1.5-2 feet deep. The light is poor, but most of the terrain that was steep enough to slide, slid.
This avalanche released in a bowl south of Copper Mountain in the Banner Summit zone. It broke 18-20" deep and several hundred feet wide. E facing slope at 8600'.
Snowpit at 8800' on an E aspect near Copper Mountain in the Banner Summit zone. The test failed 2' deep (ECTP14) on the very weak facet layer. This pit was located above a slope that avalanched naturally.