Picture taken on Alex Lowe Peak from Mount Blackmore. This is the second time this avalanche path released. See a photo from 1/25/20 HERE. Photo: Zane Heaton
Northern Gallatin
Large natural avalanche in Middle/Bear Basin
We encountered a natural avalanche that appears to have been triggered by a cornice drop. There seemed to be very little fresh snow on the slide surface so we suspect it occurred recently (Feb 14?). The slide occurred on the west side (east facing side) of Bear Basin (pinpoint on the map below). The avalanche was probably 200 feet wide at the top so it clearly propagate across the slope. Crown was 2 to 5 feet tall. We did not hike in there to investigate more carefully. There is a fair amount of trees on this part of the ridge. The picture shows how some large chunks got hung up on trees but we could see that the slide ran across the creek below (almost 1000 vertical feet). We had planned on skiing this slope and/or the open meadow (talus field) a hundred yards north but in light of this observation we turned around, skied back down in Middle Basin in the trees. Side note: we dug a pit earlier on an almost identical aspect (on the Beehive/Middle basin ridge) and obtained ECTN 16 @ 12" below the surface, ECTN 23 @4" below that, ECTN 28 @ 6" below that... Basically some definition between the latest storm layers but no propagation, and a right-side up snow pack. We only dug about 3 feet deep so this pit did not assess the ground level facets, which we figure are wide spread. The natural slide we encountered one ridge over seemed to be a case where a thin area was triggered by a cornice drop.
Large natural avalanche in Divide Basin, Hyalite
1. Observed a sizable deep slab in the Divide basin which appeared to have run within the last few days. The crown extended from the southern end of the basin (northeast facing) through the summit run off Divide (southeast facing)--maybe around a mile. Slab height varied, with the upper end pushing 10 feet and the lower closer to a foot or two. On Divide, the crown approached the summit and debris had run across the flat to the mature trees. Looked like it may have been cornice triggered at the southern end on thinner cover in rocky terrain.
2. Skied the NE shoulder of Divide Peak. Spotted a 1/4 to 1/2 mile long crown spotted along the NE face of Peak 10,024, between Divide Peak and Hyalite Peak. We could not directly determine the crown height, but it was highly visible from our location ~1 mile away.
3. Several large avalanches along the west ridge of divide basin. Appeared to be set off by large cornice drops that propagated across the bowls and stepped down several feet into the snowpack.
Observed a sizable deep slab in the Divide basin which appeared to have run within the last few days. The crown extended from the southern end of the basin (northeast facing) through the summit run off Divide (southeast facing)--maybe around a mile. Slab height varied, with the upper end pushing 10 feet and the lower closer to a foot or two. On Divide, the crown approached the summit and debris had run across the flat to the mature trees. Looked like it may have been cornice triggered at the southern end on thinner cover in rocky terrain.
Forecast link: GNFAC Avalanche Forecast for Sun Feb 16, 2020
Observed a sizable deep slab in the Divide basin which appeared to have run within the last few days. The crown extended from the southern end of the basin (northeast facing) through the summit run off Divide (southeast facing)--maybe around a mile. Slab height varied, with the upper end pushing 10 feet and the lower closer to a foot or two. On Divide, the crown approached the summit and debris had run across the flat to the mature trees. Looked like it may have been cornice triggered at the southern end on thinner cover in rocky terrain.
Observed a sizable deep slab in the Divide basin which appeared to have run within the last few days. The crown extended from the southern end of the basin (northeast facing) through the summit run off Divide (southeast facing)--maybe around a mile. Slab height varied, with the upper end pushing 10 feet and the lower closer to a foot or two. On Divide, the crown approached the summit and debris had run across the flat to the mature trees. Looked like it may have been cornice triggered at the southern end on thinner cover in rocky terrain.
Skied the NE shoulder of Divide Peak. Spotted a 1/4 to 1/2 mile long crown spotted along the NE face of Peak 10,024, between Divide Peak and Hyalite Peak. We could not directly determine the crown height, but it was highly visible from our location ~1 mile away. Photo: Tom Kalakay
Forecast link: GNFAC Avalanche Forecast for Sun Feb 16, 2020
Remotely triggered avalanches on Garnet Mtn.
Two avalanches simultaneously remotely triggered by skiers on Wednesday, 2/12/2020.
From email: "NW aspect at 8000 ft on Garnet Mountain. Two slides, one 15 feet across and one 10 feet across, remotely triggered from 15 ft away. Crown was about four feet deep, triggered on the facets. Didn't travel more than 30 vertical feet. One slide triggered in dense trees, and both slides traveled into densely treed areas. The snowpack was relatively shallow in the area where slide was triggered. Signs of instability were noted (Back on low angle terrain, after triggering the above slide), Cracks that propagated out 10+feet and were very deep and whomphing."
An avalanche on Garnet Mountain that was was remotely triggered by skiers on Wednesday, 2/12/2020. It broke 4 ft deep on facets at the ground.
Forecast link: GNFAC Avalanche Forecast for Fri Feb 14, 2020GNFAC Avalanche Forecast for Sat Feb 15, 2020