Northern Gallatin

Skiers triggered this avalanche on Flanders Mountain on 1/9/21. It was triggered out of the photo to the right on a seperate slope around the corner. It propagated over 1000' wide, and looks to be 6' deep at deepest. Photo: A. Blackmer

Skiers triggered this avalanche on Flanders Mountain on 1/9/21. It propagated around the corner over 1000' wide into an adjacent path.

From obs: "We dug a pit and found a really weak snowpack! Regardless of the poor stability result, we proceeded to ski an East facing bowl south of Flanders Mountain knowing that the slope angle was low and only flirted with 30 degrees in some parts of the bowl.... My partner skied first, he skied practically all the way back to the skin track when the slope failed and the entire bowl released. He was pretty well out of the way of danger by the time the bowl began to move. From our perspective, the trigger happened at the bottom of the slope.

We dug a pit and found a really weak snowpack! Snowpilot pit attached below. Regardless of the poor stability result, we proceeded to ski an East facing bowl south of Flanders Mountain knowing that the slope angle was low and only flirted with 30 degrees in some parts of the bowl. We could have chosen to ski the trees further to our left, but after evaluating the consequence associated with skiing the bowl, we decided that the center of the bowl did not pose too big a risk given we skied one at a time. My partner skied first, he skied practically all the way back to the skin track when the slope failed and the entire bowl released. He was pretty well out of the way of danger by the time the bowl began to move. From our perspective, the trigger happened at the bottom of the slope. The avalanche code roughly: SS-A-AS-R4-D2-O. The bowl was not the only slope that slid, the avalanche propagated around the ridge and released a slide on the more south-easterly facing aspect just south of the bowl. We tail-tucked and went home glad no one was caught or hurt.

From obs: "I went up Blackmore [1/9/21]... A pit on a south aspect at 9400’ had 100 cm, and failed at ECTP22 on large, loose facets underlying a crust about 50 cm down. A pit on a north aspect at 9400’ had 105 cm and failed at ECTP20 on the same layer, although the crust was close to nonexistent on this aspect. The snowpack overall was weaker and less consolidated here. A pit on an east aspect at 9400’ had 135 cm, and failed at ECTP25 on the same layer as the other two. I experienced a couple collapses while in shallower, treed areas on north and south aspects today.