20-21

Skier triggered wind slab in Hyalite

Overlook Mountain
Northern Gallatin
Code
SS-ASc-R2-D1.5-S
Elevation
9600
Latitude
45.40500
Longitude
-110.94200
Notes

From obs: "...We continued up and decided to stick to a ridgeline with trees in order to avoid the surrounding gullies which we believed may be cross-loaded. Near the top of the ridge (Around 9800') our options narrowed to either committing to climbing a gully or turning around, and after a couple hand shears we noticed the new snow was becoming stiffer and sliding easily on the crust so we ripped skins and turned around. 

Our route had one area of concern on the way down, which was a small gully between a cliff band. I made a ski cut towards the top since the terrain had (relatively) lower consequence and was able to release a wind slab roughly 4-6" deep. The deeper area to the right was the descent track from group members 2 and 3 after the wind slab had released."

Number of slides
1
Number caught
0
Number buried
0
Avalanche Type
Soft slab avalanche
Trigger
Skier
Trigger Modifier
c-A controlled or intentional release by the indicated trigger
R size
2
D size
1.5
Bed Surface
S - Avalanche released within new snow
Problem Type
Wind-Drifted Snow
Slab Thickness
6.0 inches
Slab Width
30.00ft
Slab Thickness units
inches
Single / Multiple / Red Flag
Single Avalanche
Advisory Year

From obs: "Deep slab avalanche in Blackmore Basin that appeared to break on the depth hoar near the bottom of the snowpack. It was on a wind loaded NE facing slope at approx. 9,500 and looked to break on a slope in the 35-40 degree range. The crown was about 8'-10' deep and 200' wide. It broke to the ground and ripped out several small trees." Photo: JR Mooney

Northern Gallatin, 2021-03-27

Skier remote triggered deep slab near Mt Blackmore

Mt Blackmore
Northern Gallatin
Code
HS-ASr-R2-D2-O
Elevation
9500
Aspect
NE
Latitude
45.44070
Longitude
-110.99900
Notes

From obs: "Skied Mount Blackmore today. around 1 pm a skier remote triggered a deep slab from ~50 feet away (around the corner lookers right in the attached picture). Broke at the ground, 10-15feet deep, and took out a small tree."

From obs: "My partner and I observed a deep slab avalanche in Blackmore Basin that appeared to break on the depth hoar near the bottom of the snowpack. It was on a wind loaded NE facing slope at approx. 9,500 and looked to break on a slope in the 35-40 degree range. The crown was about 8'-10' deep and 200' wide. It broke to the ground and ripped out several small trees. As soon as we saw it, we came over a small ridge to see another skier near the debris. According to him it was triggered remotely by one of the two skiers on the coming down on the lookers right of the slide ... We confirmed that a beacon search was done to make sure no one was buried."

Number of slides
1
Number caught
0
Number buried
0
Avalanche Type
Hard slab avalanche
Trigger
Skier
Trigger Modifier
r-A remote avalanche released by the indicated trigger
R size
2
D size
2
Bed Surface
O - Old snow
Problem Type
Persistent Weak Layer
Slab Thickness
90.0 inches
Vertical Fall
220ft
Slab Width
50.00ft
Weak Layer Grain type
Depth Hoar
Slab Thickness units
inches
Single / Multiple / Red Flag
Single Avalanche
Advisory Year

Skier triggered wind slabs Mt Blackmore

Mt Blackmore
Northern Gallatin
Code
SS-AS-R1-D1
Elevation
9500
Aspect
E
Latitude
45.44250
Longitude
-111.00100
Notes

From obs: "Observed a small skier triggered slide on the middle ridge of MT Blackmore today, skier was cutting across when it released."

From obs: "Skied Mount Blackmore today. There was a lot more new snow than expected (6-8") and ridgetop winds were strong and gusty. Snow along the ridgelines and on E-facing slopes was touchy. Lots of cracking and collapsing. Saw 4 skier triggered slides on the E face between the Blackmore and Alex Lowe Basins. Most appeared to be wind slabs,..."

Number of slides
5
Number caught
0
Number buried
0
Avalanche Type
Soft slab avalanche
Trigger
Skier
R size
1
D size
1
Problem Type
Wind-Drifted Snow
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Multiple Avalanches
Advisory Year

Natural avalanches in Hyalite: A Lowe peak, Flanders

Flanders Creek
Northern Gallatin
Code
HS-N-R2-D2
Elevation
9500
Aspect
N
Latitude
45.44020
Longitude
-110.93100
Notes

From obs: "Skied Mount Blackmore today. Saw a natural avalanche on Alex Lowe peak just south of the Hellmouth,..."

Other group's obs: "I and one friend observed the remains of a natural avalanche below the north facing headwall up Flanders creek. It looked as if it happened within the past few days. I didn’t get close enough to really gauge the size in width but it propagated at the ground. The crown looked to be 3’-4’ deep..."

Number of slides
2
Number caught
0
Number buried
0
Avalanche Type
Hard slab avalanche
Trigger
Natural trigger
R size
2
D size
2
Problem Type
Persistent Weak Layer
Slab Thickness
36.0 inches
Slab Thickness units
inches
Single / Multiple / Red Flag
Multiple Avalanches
Advisory Year