Northern Gallatin

Bridger patrol triggered deep slab

Bridger Bowl
Bridger Range
Code
HS-ABc-R4-D3-O
Elevation
8500
Aspect
NE
Latitude
45.81560
Longitude
-110.92300
Notes

This slide was triggered by Bridger Bowl ski patrol during control work on Saturday (1/4/2020) on "The Drain". This is a heavily wind loaded slope on the south end of the ski area adjacent to the backcountry (Saddle Peak). It shows deeply buried persistent weak layers from early October and November were pushed to a breaking point by the recent snow and wind.

Number of slides
1
Number caught
0
Number buried
0
Avalanche Type
Hard slab avalanche
Trigger
An explosive detonated above the snow surface (air blast)
Trigger Modifier
c-A controlled or intentional release by the indicated trigger
R size
4
D size
3
Bed Surface
O - Old snow
Problem Type
Persistent Weak Layer
Slab Thickness
48.0 inches
Vertical Fall
1000ft
Slab Width
100.00ft
Images
Bridger patrol triggered deep slab debris
Bridger patrol triggered deep slab avalanche 2
Bridger patrol triggered deep slab avalanche
Slab Thickness units
inches
Single / Multiple / Red Flag
Single Avalanche
Advisory Year
19-20

This slide was triggered by Bridger Bowl ski patrol during control work on Saturday (1/4/2020). It shows deeply buried persistent weak layers from early October and November were pushed to a breaking point by the recent snow and wind. A person can trigger avalanches like this on heavily wind loaded slopes in the backcountry. Additionally, shallower large avalanches can be triggered on any steep slope. Photo: BBSP

Avalanche Details: Bridger patrol triggered deep slab
Forecast link: GNFAC Avalanche Forecast for Sun Jan 5, 2020
Bridger Range, 2020-01-04
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    • A party of three skiers remote triggered avalanche with at least 6' crown off N face of Mt Porphry along rockband near summit on 12/29/19. They triggered it after tyhey had found "Three pits dug on NE face ascending Mt Porphry indicating increasing stability and no clean propagation. Approx 150-210 cm deep snowpack." Photo: G. Alsentzer

    Avalanche Details: Remote triggered 6' deep in Tobacco Root Mtns
    Forecast link: GNFAC Avalanche Forecast for Sat Jan 4, 2020GNFAC Avalanche Forecast for Sun Jan 5, 2020
    Out of Advisory Area, 2020-01-03
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    • Small skier triggered avalanche near Mt Blackmore Trail, Hyalite

    Mt Blackmore
    Northern Gallatin
    Code
    ASu-R0-D1
    Elevation
    9000
    Aspect
    NW
    Latitude
    45.44730
    Longitude
    -110.99900
    Notes

    From an email:

    "Also observed a recent slide on the northwest face of elephant, at about 9000 feet, in the second elephant glade along the blackmore trail. Wind pocket looked to be triggered by a skier on their way out, maybe 30 feet wide, ran for a 80 feet. Looks like they stayed high, just below a rock band on their exit and cut the wind slab."

    Number of slides
    1
    Number caught
    0
    Number buried
    0
    Trigger
    Skier
    Trigger Modifier
    u-An unintentional release
    R size
    0
    D size
    1
    Problem Type
    Wind-Drifted Snow
    Slab Thickness units
    centimeters
    Single / Multiple / Red Flag
    Single Avalanche
    Advisory Year
    19-20

    Ice climber hit by loose snow avalanche on Killer Pillar, Hyalite

    Flanders Creek
    Northern Gallatin
    Code
    L-N
    Aspect
    NE
    Latitude
    45.44020
    Longitude
    -110.93100
    Notes

    From an email:

    "Got hit by a pretty decent loose snow avalanche from above while topping out on Killer Piller up Flanders. Had a decent stance so I was able to hold on. Also observed more than a few coming down gullies on the other side of the drainage. It was lightly snowing all day and dead calm in the drainage, so presumably winds were cranking on the ridgetop."

    Number of slides
    1
    Number caught
    0
    Number buried
    0
    Avalanche Type
    Loose-snow avalanche
    Trigger
    Natural trigger
    Problem Type
    Wind-Drifted Snow
    Slab Thickness units
    centimeters
    Single / Multiple / Red Flag
    Single Avalanche
    Advisory Year
    19-20

    Skier remotely triggered a small wind slab up Hyalite

    Maid of the Mist
    Northern Gallatin
    Code
    SS-ASr-R0-D1-I
    Latitude
    45.41640
    Longitude
    -110.97000
    Notes

    From an email: "Remotely triggered this small wind slab while skinning into the Maid of the Mist basin. Throughout the day I continued to encounter other small, reactive wind slabs and strong winds."

    Number of slides
    1
    Number caught
    0
    Number buried
    0
    Avalanche Type
    Soft slab avalanche
    Trigger
    Skier
    Trigger Modifier
    r-A remote avalanche released by the indicated trigger
    R size
    0
    D size
    1
    Bed Surface
    I - Interface between new and old snow
    Problem Type
    Wind-Drifted Snow
    Images
    Skier remotely triggered a small wind slab in Hyalite
    Slab Thickness units
    centimeters
    Single / Multiple / Red Flag
    Single Avalanche
    Advisory Year
    19-20

    This small wind slab was remotely triggered while skinning into the Maid of the Mist basin. Throughout the day they continued to encounter other small, reactive wind slabs and strong winds. Small avalanches are a warning sign that larger ones are possible. Photo: Sam Wilson

    Avalanche Details: Skier remotely triggered a small wind slab up Hyalite
    Forecast link: GNFAC Avalanche Forecast for Wed Jan 1, 2020GNFAC Avalanche Forecast for Fri Jan 3, 2020
    Northern Gallatin, 2019-12-31
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