Northern Gallatin

A skier remotely triggered an avalanche on Mt Blackmore (11/9/22).

From email: "I ski cut the top of the face and remote triggered a hard slab from 50’ above the crown. It broke full width of the couloir feature, 150’ wide and 10-18” deep. Broke on new snow/old snow interface which was another hard wind slab. The avalanche ran the length of the East face and stopped just below the last set of cliffs."

A skier remotely triggered an avalanche on Mt Blackmore (11/9/22).

From email: "I ski cut the top of the face and remote triggered a hard slab from 50’ above the crown. It broke full width of the couloir feature, 150’ wide and 10-18” deep. Broke on new snow/old snow interface which was another hard wind slab. The avalanche ran the length of the East face and stopped just below the last set of cliffs."

Today I got reassuring results from a snow pit dug at 9195' on a Northeast aspect (40 degrees) in the basin between Mt. Blackmore and Elephant Peak. The area was clearly wind-loaded with an HS of 110cm. I got a CT20, Q2 @ 50cm (see image), a resistant planar failure that appeared to occur on a thin layer of decomposing fragments. In my ECT, I received no results whatsoever, so I sense that this weak layer is quite unlikely to react, though structurally the snow consisted of a hard wind slab on top of an identifiable weak layer.

I also performed an analysis and multiple ECTs on a snow wall closer to Elephant Mountain (8950'), which was a Northwestern aspect (318 degrees). The snow wasn't as deep at this location (HS 73cm), and my results were ECTN22 @ 42cm, then ECTN21 @ 44cm (see images).

I hope these results are helpful as we begin to wrap our heads around this early season snowpack.

Thanks,

Charlie

While traveling up the Fairy Lake road, we observed the aftermath of an avalanche in October Bowl. The avalanche was D2-D3, start zone was at approximately 9000 ft, north east aspect, crown depth and width is unknown. Photo: H. Bigos-Lowe

Skiers found a thin snowpack that is beginning to weaken (facet). Read observation here. Photo: T McCutcheon.

Went for a short walk in the Bridgers this afternoon (3-11-2022) for a few turns, and to get eyes on how the snowpack is shaping up. We headed from the base to the terrain above Alpine. In the apron of Hidden Gulley, two small dry loose sluffs were visible. Another dry loose sluff was present further north on the ridge. They all appeared to be natural. A photo has been attached. Deciding the apron was too thin for turns, myself and my partner opted to traverse to Bradley Meadow. 

On the way, we dug a quick pit at about 7500 feet on a shaded NE aspect (photo attached). Close to the ground, mixed forms were present with pretty clear faceting occurring. A stout sun crust capped the old snow. Atop the crust and beneath the new snow was a clear layer of large graupel particles, potentially setting the stage for a weak layer with high spatial variability down the road. Deepest snow depth recorded in a shaded area was approximately 50cm. 

Our primary hazard today was the rocks and stumps associated with early season conditions.

An observer saw evidence of wind loading creating the conditions for avalanches in the Bridger Range on Sunday. Cracking is an indicator of instability. The observer noted that the relatively small drift he saw was "nothing consequential," but this shows that unstable drifts are forming. They will be more consequential where there is more snow and as the wind creates larger drifts. 

Evidence of wind-loading creating the conditions for avalanches in the Bridger Range. Cracking is an indicator of instability. The observer noted this was "Nothing consequential," but this shows that unstable drifts are forming. They will be more consequential where there is more snow and as the wind creates larger drifts. Photo: E Smith