Close
Missoula Avalanche

Public Observation

Observation Details

Observation Date:
January 9, 2022
Submitted:
January 10, 2022
Zone or Region:
Activity:
Skiing/Snowboarding
Location:
Big Saint Joe, Bitterroot

Observed Avalanches

Did you observe any avalanches? 
Yes
Avalanche Type:
Soft Slab
Size:
Size 3: Could bury and destroy a car, damage a truck, destroy a wood frame house, or break a few trees
Elevation:
8000 - 9500 crown elevaions
Aspect:
Comments:
Multiple crowns observed. N. face of the West bowl of Lappi had a large crown near the ridge line. The entire Southeast bowl of Big Saint Joe avalanched during the storm last week. Crowns around the entire head of the bowl. Debris extended slightly farther down the Southeast ramp than usual - it was a pretty big slide. There were presumably some smaller naturals that happened during the storm where debris had already been buried by subsequent snow and wind.

Signs of Unstable Snow

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

Observations

We skied Big Saint Joe in Bass creek on Sunday via the Southeast ramp. Natural observations are noted above. We dug a quick low elevation pit at 6,000 feet on a steep south facing wind protected site to assess steep terrain required to gain the upper mountain. We did not dig a pit in a more conventional mid-elevation location. Total snow depths were about 150 cm. Test results were ECTN11 25 cm down from the surface (I think this was the Friday precipitation interface) and ECT14 40 cm down (I think this was a density change on cold snow from the beginning of last week's large precipitation event). We were also getting isolated cracking around switchbacks, indicating the new snow had not stabilized quite yet.

We observed little to no cracking or acute signs of instability at mid and upper elevations, but we also weren't on steep terrain. Based on not hearing any collapsing, no signs of post-storm avalanche activity, our intuitive sense was that the snowpack was handling the massive load fairly well, and that new snow was stabilizing rapidly, but that the new snow had not stabilized quite yet.

Temperatures were inverted, and we did not note any surface hoar growth.

Snow coverage in Bass creek is really good.

Media

Crown and debris locations on the Southeast face of Big Saint Joe.
Close