From IG 12/12/21: @montanamountainmedicine
Northern Gallatin
Collapses and Whumphs on NE Aspect 8000 feet in Hyalite
Hyalite - East Fork
Northern Gallatin
Code
AF-O
Elevation
8000
Aspect
NE
Latitude
45.45050
Longitude
-110.91900
Notes
From email obs: 12/12/21: "Shooting cracks and whoomphing in wind loaded areas. An approximately 15x30ft wind slab cracked along the bas of a rock band and settled at the base of P2 on high fidelity. Was triggered while traversing along the rock band to gain the second pitch, 1-2 inches of facets on the ground. Wind slab of 6-36in in the gullies."
(Second photo, believed to be from different group, sent on IG)
Number caught
0
Number buried
0
Trigger
Foot penetration
Bed Surface
O - Old snow
Problem Type
Wind-Drifted Snow
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Red Flag
Advisory Year
From obs: 12/12/21: "Shooting cracks and whoomphing in wind loaded areas. An approximately 15x30ft wind slab cracked along the base of a rock band and settled at the base of P2 on high fidelity. Was triggered while traversing along the rock band to gain the second pitch, 1-2 inches of facets on the ground. Wind slab of 6-36in in the gullies." Photo: M. Hearley
Hyalite Canyon, North of elephant mountain
Date
Activity
Skiing
Dug a pit on a northeast aspect at 8000’. Performed a CT and ECT. Both collapsed vertically on 26 in facet layer in between base crust and new wind slab. No propagation, no major weak layer failure.
Region
Northern Gallatin
Location (from list)
Elephant Mountain
Observer Name
Harrison Bigos-Lowe
West Ridge of East Fork -NE Aspect 8000 feet - High Fidelity
Date
Activity
Ice Climbing
Shooting cracks and whoomphing in wind loaded areas. An approximately 15x30ft wind slab cracked along the bas of a rock band and settled at the base of P2 on high fidelity. Was triggered while traversing along the rock band to gain the second pitch, 1-2 inches of facets on the ground. Wind slab of 6-36in in the gullies.
Region
Northern Gallatin
Location (from list)
Hyalite - East Fork
Observer Name
Matthew Hearley
In the Bridger Range on December 10, 2021 2-3" of low density new snow was drifted into small soft slabs that were easy to trigger. Photo: GNFAC
Avalanche Details: small (very small) wind slabs
Forecast link: GNFAC Avalanche Forecast for Sat Dec 11, 2021GNFAC Avalanche Forecast for Sun Dec 12, 2021
Bridger Range, 2021-12-10
Forecast link: GNFAC Avalanche Forecast for Sat Dec 11, 2021GNFAC Avalanche Forecast for Sun Dec 12, 2021
This pit was dug in Hyalite Canyon near Twin Falls. It showed 2 mm facets (sugar snow) underlying the snowpack. This layer did not break in stability tests, but anticipate these grains will get weaker with time. Photo: GNFAC