20-21

Yellowstone National park (Chrystal Creek); cornice collapse and whumpfs

Out of Advisory Area
Code
C-AS
Latitude
44.88990
Longitude
-110.33300
Notes

In Lamar Valley:

Today in Chrystal Creek my group of 4 skiers triggered 3 cornices. 2 remotely triggered and one small one while skiing off of it. The slope below was not steep enough to slide far. ~75cm of snow where we dug our pit on a North slope at 26 degrees. One slab ~23cm off the ground didn’t cause any real problems. Another hard slslab35cm-42cm sitting on facets broke at ECTP7, CTPV. Had more whumphs than we could count and cracks that shot 30+ meters. Snow depth varied greatly, some wiwind loading

Number of slides
1
Number caught
0
Number buried
0
Avalanche Type
Cornice fall
Trigger
Skier
Images
A small cornice collapse in YNP
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Single Avalanche
Advisory Year
20-21

In Lamar Valley:

Today in Chrystal Creek my group of 4 skiers triggered 3 cornices. 2 remotely triggered and one small one while skiing off of it. The slope below was not steep enough to slide far. ~75cm of snow where we dug our pit on a North slope at 26 degrees. One slab ~23cm off the ground didn’t cause any real problems. Another hard slab ~35cm-42cm sitting on facets broke at ECTP7, CTPV. Had more whumphs than we could count and cracks that shot 30+ meters. Snow depth varied greatly, some wind loading.

Avalanche Details: Yellowstone National park (Chrystal Creek); cornice collapse and whumpfs
Out of Advisory Area, 2021-01-05
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    • Collapses, cracking and a natural avalanche on Mineral Mountain

    Mineral Mountain
    Cooke City
    Code
    SS-N
    Latitude
    45.03030
    Longitude
    -109.99800
    Notes

    New snow:  about 6" of fresh in town- from last night.

    We observed a few fresh natural avalanches out there today.  Photo of one attached:  a S, SE asaspectn Mineral Mountain.  That slislideoked to have occurred last night, and is estimated to be around 4-500' wide.
     
    There were also a handful of smaller slab avalanches on NW though NE aspects in the cirque of Mt. Republic, which looked to be more like 36-48 hrs old.
     
    Quite a few large collapses experienced today as well- in the mid and upper elevations.
    Number caught
    0
    Number buried
    0
    Avalanche Type
    Soft slab avalanche
    Trigger
    Natural trigger
    Images
    Natural Avalanche on Mineral Mountain
    Slab Thickness units
    centimeters
    Single / Multiple / Red Flag
    Multiple Avalanches
    Advisory Year
    20-21

    We observed a few fresh natural avalanches out there today... a S, SE aspect on Mineral Mountain.  That slide looked to have occurred last night, and is estimated to be around 4-500' wide. Photo: B. Fredlund
     
    Avalanche Details: Collapses, cracking and a natural avalanche on Mineral Mountain
    Forecast link: GNFAC Avalanche Forecast for Wed Jan 6, 2021
    Cooke City, 2021-01-05
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    • Scotch Bonnet and Sheep Basin/Wolverine Peak natural avalanches

    Scotch Bonnet
    Cooke City
    Code
    L-N
    Aspect Range
    E-SE
    Latitude
    45.05660
    Longitude
    -109.95100
    Notes

    Cooke got 6" (.6" SWE) last night.

    1. Natural, unwitnessed avalanche on Scotch Bonnet, S aspect.

    2. Natural avalanche on SE wind loaded slope in Sheep Basin - Wolverine Peak.

    Number of slides
    2
    Number caught
    0
    Number buried
    0
    Avalanche Type
    Loose-snow avalanche
    Trigger
    Natural trigger
    Problem Type
    New Snow
    Images
    Scotch Bonnet loose snow avalanches
    Slab Thickness units
    centimeters
    Single / Multiple / Red Flag
    Multiple Avalanches
    Advisory Year
    20-21

    Skier triggered avalanche on Henderson Mtn

    Henderson Bench
    Cooke City
    Code
    SS-ASr-O
    Elevation
    9500
    Aspect
    S
    Latitude
    45.04080
    Longitude
    -109.94000
    Notes

    Remote triggered a soft slab with a ski cut. Cut across top of slope and the slide initiated ten yards below. slide was approximately 25 feet at the crown and ran the whole length/ width of the gulley. Couldn’t see past the choke of the gulley . Thicker at the crown where snow was wind drifted 16 in~. Dug a quick pit after. HS 80 cm. SlSlabn top of crust and facets. No one was caught and we skinned back up and skied out our original skin trtrack

    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
    Bed Surface
    O - Old snow
    Problem Type
    Persistent Weak Layer
    Slab Thickness
    16.0 inches
    Slab Width
    25.00ft
    Weak Layer Grain type
    Faceted Crystals
    Images
    Skier triggered avalanche on Henderson Mtn_path
    Skier triggered avalanche on Henderson Mtn_crown
    Slab Thickness units
    inches
    Single / Multiple / Red Flag
    Single Avalanche
    Advisory Year
    20-21

    Remote triggered a soft slab with a ski cut. Cut across top of slope and the slide initiated ten yards below. slide was approximately 25 feet at the crown and ran the whole length/ width of the gulley. Couldn’t see past the choke of the gulley. Thicker at the crown where snow was wind drifted 16 in~. Dug a quick pit after. HS 80 cm. Slab on top of crust and facets. No one was caught and we skinned back up and skied out our original skin track. Photo: S. Brown

    Avalanche Details: Skier triggered avalanche on Henderson Mtn
    Cooke City, 2021-01-05
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    • Remote triggered a soft slab with a ski cut. Cut across top of slope and the slide initiated ten yards below. Slide was approximately 25 feet at the crown and ran the whole length/ width of the gulley. Couldn’t see past the choke of the gulley. Thicker at the crown where snow was wind drifted 16 in~. Dug a quick pit after. HS 80 cm. Slab on top of crust and facets. No one was caught and we skinned back up and skied out our original skin track. Photo: S. Brown

    Avalanche Details: Skier triggered avalanche on Henderson Mtn
    Forecast link: GNFAC Avalanche Forecast for Wed Jan 6, 2021
    Cooke City, 2021-01-05
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    • Collapse and crack in Lick Creek

    Lick Creek
    Northern Gallatin
    Code
    Latitude
    45.52430
    Longitude
    -110.95600
    Notes

    A skier got a collapse and crack in Lick Creek. The collapse has sizeable displacement which is indicative of a very thick and unstable weak layer.

    Number of slides
    0
    Number caught
    0
    Number buried
    0
    Images
    Collapse and crack in Lick Creek
    Slab Thickness units
    centimeters
    Single / Multiple / Red Flag
    Red Flag
    Advisory Year
    20-21
    Subscribe to 20-21