Sawtooth Avalanche Center

Public Field Report

Observation Details

Observation Date:
December 20, 2019
Submitted:
December 20, 2019
Zone or Region:
Banner Summit
Activity:
Skiing/Snowboarding
Location:
Copper

Observed Avalanches

Did you observe any avalanches? 
Yes
Avalanche Type:
Soft Slab
Size:
Size 2: Could bury, injure, or kill a person
Elevation:
8865ft
Aspect:
N
Comments:
Saw multiple Avalanches that I think went mid storm due to wind loading the slopes. Look to have most likely went on the 12/7 SH layer.
Photo:

Signs of Unstable Snow

Did you see shooting cracks? 
No
Did you experience collapsing or whumpfing? 
Yes, Isolated

Observations

Was very warm today when left truck it was 33 degrees at 10:30 am at 7,000 ft. When I return in the later afternoon it was 37 degrees. Calm wind below 8,000 ft then was Moderate from the SW. with strong gusts above 8,000 ft definitely windier the high you got transporting snow. With this storm and the wind that came with it really stiffened the top 10-15cm of snow. The SH layer was there but had broken down to 1-2mm grains instead of the 2-3cm SH grains I saw in the area back on 12/6 before they got buried. So things might be getting less sensitive now but you never know if you will find that sweet spot and the dragon.

Media

Looking back at Copper. Slab pulled out at after the slopes rollsover. Must of went mid storm the starting area had new blown snow on it. Also small cornice blocks released
Looking South down the ridge line see multiple crowns. Most likely went mid storm part of the crowns were starting to get covered up.
You can definitely see the problem layers in there SH 12/7 layer at 55cm. The 11/26 layer at 38cm.

Advanced Observations

Observed Avalanche Problem #1: 
Wind Slab
Comments: 
With the wind up at the upper elevations transporting snow onto the N and NE aspect we will most likely have a stiff wind slab building on top of week snow.
Observed Avalanche Problem #2: 

Comments: