Northern Gallatin
Natural and human triggered wind slab avalanches in Hyalite
Hyalite - main fork
Northern Gallatin
Code
SS
Latitude
45.44720
Longitude
-110.96200
Notes
Observations from Hyalite today:
1. When approaching the base of Mt. Blackmore this morning at roughly 8:45am we observed strong swirling winds at higher elevations (summit of Blackmore and the Elephant/Blackmore Saddle). The winds we observed were primarily loading snow onto E and SE facing aspects. Furthermore, we witnessed four naturally triggered avalanches over a twenty minute span. All slides appeared to be D1/D2 on E and SE aspects and, seemingly, restricted to the newly loaded snow.
2. My partner and I climbed Zach Attack today. We intentionally triggered numerous size 1 wind slabs in the gully approaching the climb, which has slopes up to 35 degrees. These slabs were between 5 and 15 cm thick, up to 5m wide, 4F in hardness, touchy, and failed on lower density new snow. Although none of them ran more than 20m in this terrain, it would be a different story on steeper slopes, and if you were in an exposed position they had enough mass to push you around. Strong down and cross-slope winds formed these slabs at and below treeline, while the more alpine terrain of the climb itself was scoured.
3. Skied up in the main drainage of Hyalite today. Triggered some small wind slabs and propagating cracks. We backed off our main objective (a north facing couloir) because of these red flags and multiple crown lines on the same aspect and elevation.
Number caught
0
Number buried
0
Avalanche Type
Soft slab avalanche
Problem Type
Wind-Drifted Snow
Images
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Multiple Avalanches
Advisory Year
This avalanche of wind-drifted snow was triggered with a ski cut on a southeast aspect at 9,800'. Photo: T. Chingas
This slide was triggered up Hyalite from 100' away. It was a wind loaded slope at 9,000', northeast aspect. Photo: T. Chingas
Avalanche Details: Natural and human triggered wind slab avalanches in Hyalite
Forecast link: GNFAC Avalanche Forecast for Mon Dec 2, 2019
Northern Gallatin, 2019-12-01
Forecast link: GNFAC Avalanche Forecast for Mon Dec 2, 2019
From an observation:
When approaching the base of Mt. Blackmore this morning at roughly 8:45am we observed strong swirling winds at higher elevations (summit of Blackmore and the Elephant/Blackmore Saddle). The winds we observed were primarily loading snow onto E and SE facing aspects. Furthermore, we witnessed four naturally triggered avalanches over a twenty minute span. All slides appeared to be D1/D2 on E and SE aspects and, seemingly, restricted to the newly loaded snow. Photo: SAM
Avalanche Details: Natural and human triggered wind slab avalanches in Hyalite
Northern Gallatin, 2019-12-01
From an observation:
When approaching the base of Mt. Blackmore this morning at roughly 8:45 am we observed strong swirling winds at higher elevations (summit of Blackmore and the Elephant/Blackmore Saddle). The winds we observed were primarily loading snow onto E and SE facing aspects. Furthermore, we witnessed four naturally triggered avalanches over a twenty minute span. All slides appeared to be D1/D2 on E and SE aspects and, seemingly, restricted to the newly loaded snow. Photo: SAM
Natural and human triggered wind slabs in the Bridger Range
Saddle Peak
Bridger Range
Code
SS-N-D2
Aspect
E
Latitude
45.79430
Longitude
-110.93600
Notes
From an email:
"I toured up Bridger today... We found reactive windslabs at the ridgeline. On the drive up we observed a few small avalanches in Mundies Bowl and a larger (D2) slide just north of Saddle’s north summit. All appeared to be windslabs that released at the ridgeline. We dug a pit a few hundred feet below the ridge above the entrance to 2 Way and Stuper. I’ve attached a photo of this, as well as of windslabs at the ridgeline and one of the flank of the slide on Saddle"
Number caught
0
Number buried
0
Avalanche Type
Soft slab avalanche
Trigger
Natural trigger
D size
2
Problem Type
Wind-Drifted Snow
Images
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Multiple Avalanches
Advisory Year
This natural avalanche released on Saddle Peak. wind loading from west winds created sensitive wind slabs this morning. Photo: S. Jonas
Avalanche Details: Natural and human triggered wind slabs in the Bridger Range
Bridger Range, 2019-12-01
Skiers found reactive wind slabs near the ridge line that easily avalanched. Photo: S. Jonas
Avalanche Details: Natural and human triggered wind slabs in the Bridger Range
Bridger Range, 2019-12-01
From obs.: "New snow from 24 hours ago blew around the ridge tops from 11pm last night until 7am this morning ~30mph. This soft 4 finger slab was about 6”-7” deep and broke on a convex roll.... We were assessing the terrain carefully and expected this result." Photo: R. Christian-Frederick
Avalanche Details: Small intentionally triggered wind slab in Beehive Basin
Northern Madison, 2019-12-01