23-24

Natural Avalanche on MT Henderson

Date
Activity
Skiing

Observed this natural avalanche on the south summit of Mt Henderson. Slope is SE facing, 9800 ft. This slope is heavily wind loaded. I estimate the crown is two feet deep and the avalanche is D2. Likely occurred on Friday 12/8 

Region
Cooke City
Location (from list)
Henderson Mountain
Observer Name
Jake Mundt

GNFAC Avalanche Forecast for Sun Dec 10, 2023

Snowpack and Avalanche Discussion

<p><span><span><span><span><span><span>Yesterday was the third day in a row with reports of avalanches and widespread collapsing of the snowpack. A skier triggered and was not caught in a slide at Bridger Bowl in terrain that is currently the backcountry (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/images/23/skier-triggered-avalanche-super-c…;), natural avalanches were reported in Beehive Basin (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/29458"><span><span><span><strong><span…;), Taylor Fork (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/29455"><span><span><span><strong><span…;) and Cooke City (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/images/23/avalanche-henderson-mtn"><span><s…;), and skiers near West Yellowstone (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/29454"><span><span><span><strong><span…;) and Cooke City (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/29430"><span><span><span><strong><span…;) and climbers in Hyalite experienced large collapses (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/29460"><span><span><span><strong><span…;).</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>Across our forecast area the snowpack is unstable, and a person can easily trigger a dangerous avalanche. Slopes that had snow on the ground prior to last week’s new snow are the most dangerous, especially where recent strong winds also drifted snow into thicker slabs over the old snow. Snow that survived on the ground during November became faceted, sugary and weak and is struggling to support the weight of recent snow. We show this in our field videos over the last week from Bridger, Hyalite, Island Park, Cooke City and Lionhead (</span></span></span></span></span></span><a href="https://www.youtube.com/playlist?list=PLXu5151nmAvSH326zVaU9KXJAPtvkIt-…;). Many </span></span></span></span></span></span><a href="https://www.mtavalanche.com/snow-observations-list"><span><span><span><… observations</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span> also show signs of instability and support the need to travel cautiously in the mountains.</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>Now is not the time to travel on slopes steeper than 30 degrees. Avalanches that break on the old snow can be triggered from low angle terrain that is connected to steep slopes, so also consider terrain that is above and adjacent to you. With the recent gusty winds (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/images/23/windy-bridgers"><span><span><span…;), all wind-loaded slopes are suspect today. Be especially cautious of steep slopes that have fresh drifts, and any slope where there is old snow below last week’s snow.</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>Throughout our forecast area, human triggered avalanches are likely and the avalanche danger is CONSIDERABLE.</span></span></span></span></span></span></p>

Upcoming Avalanche Education and Events

Our education calendar is full of awareness lectures and field courses. Check it out: Events and Education Calendar.

Collapsing on ice climbs in Hyalite

Date
Activity
Ice Climbing

1 team yesterday (Saturday, not me) climbed Bobo Like and Big Sleep (first 2 pitches of each). They experienced 2x collapses but no other signed of instability.

 

Region
Northern Gallatin
Location (from list)
Flanders Creek

Natural activity in Beehive Basin

Beehive Basin
Northern Madison
Code
N
Latitude
45.34070
Longitude
-111.39100
Notes

Skiers in Beehive basin observed a natural avalanche on Saturday 12/9

Number of slides
1
Number caught
0
Number buried
0
Trigger
Natural trigger
Snow Observation Source
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Single Avalanche
Advisory Year

Skier Triggered Avalanche at Bridger Bowl

Bridger Bowl
Bridger Range
Code
SS-ASu-R2-D1.5
Latitude
45.81560
Longitude
-110.92300
Notes

From email: "Solo skier that released a small pocket of snow at the bottom of Super Couloir - he was not caught and it was just the recent new snow and it didn't run far."

Number of slides
1
Number caught
0
Number buried
0
Avalanche Type
Soft slab avalanche
Trigger
Skier
Trigger Modifier
u-An unintentional release
R size
2
D size
1.5
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Single Avalanche
Advisory Year

Natural Avalanches in Taylor Fork

Taylor Fork
Southern Madison
Code
SS-N-R1-D1
Latitude
45.06070
Longitude
-111.27200
Notes

Riders in Taylor Fork saw natural avalanches on Saturday, 12/9

Number of slides
1
Number caught
0
Number buried
0
Avalanche Type
Soft slab avalanche
Trigger
Natural trigger
R size
1
D size
1
Snow Observation Source
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Single Avalanche
Advisory Year

Widespread Cracking and Collapsing

Kirkwood Ridge
Southern Madison
Code
AS
Latitude
44.86920
Longitude
-111.23900
Notes

Skiers in the Southern Madison, Lionhead, and Northern Madison areas experienced widespread cracking and collapsing on Saturday 12/9.

Number of slides
0
Number caught
0
Number buried
0
Trigger
Skier
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Red Flag
Advisory Year