24-25

Wind slabs North of Cooke City

Date
Activity
Skiing

Today we noticed these natural small wind slabs on Mt Henderson.

 

We also observed active wet loose in Zimmer Creek today on rocky terrain. 

Region
Cooke City
Observer Name
Jake Mundt

Avalanche Saddle Peak

Date

Noticed crown and debris on drive up Bridger Canyon this morning.  Looks like a wind slab. 

Region
Bridger Range
Location (from list)
Saddle Peak
Observer Name
Peter

GNFAC Avalanche Forecast for Tue Mar 25, 2025

Snowpack and Avalanche Discussion

<p><span><span><span><span><span><span>Springtime weather brings several avalanche problems that will evolve throughout the day as temperatures warm well above freezing. Consider what avalanche problem is the most concerning at any given time and where they might overlap, because the management strategy is slightly different for each.&nbsp;</span></span></span></span></span></span></p>

<p><span><span><span><strong><span><span>Wind slab avalanches </span></span></strong></span></span></span><span><span><span><span><span><span>breaking up to a couple feet deep on slopes where winds recently drifted snow are the primary concern. Yesterday, a natural avalanche slid on a wind-loaded slope on the Fin south of Cooke City (</span></span></span></span></span></span><a href="https://mtavalanche.com/node/34742"><span><span><span><strong><span><u>… and photo</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>). While instability related to recently wind-drifted snow is decreasing, similar human-triggered avalanches are possible today. Seek out sheltered terrain and avoid heavily wind-loaded slopes immediately below cornices. Note conditions that indicate potential instability, such as a stiffening of the snow surface and shooting cracks.&nbsp;</span></span></span></span></span></span></p>

<p><span><span><span><strong><span><span>Wet loose avalanches </span></span></strong></span></span></span><span><span><span><span><span><span>will slide naturally as the day warms and the snow surface moistens and becomes weaker. These are most likely on southern aspects and slopes with exposed rocks and cliff bands that heat up in the sun. Wet snow avalanches will be relatively small, primarily a hazard in technical terrain where heavy snow could push riders or skiers into obstacles like trees, rocks and off cliffs. Move to shadier, northern aspects if more than the top few inches of snow becomes wet or you observe cinnamon-roll-like pinwheels and small wet snow avalanches in nearby terrain.&nbsp;</span></span></span></span></span></span></p>

<p><span><span><span><strong><span><span>Persistent slab avalanches </span></span></strong></span></span></span><span><span><span><span><span><span>are primarily a concern in the Lionhead, Southern Gallatin and Southern Madison Ranges, and to a lesser extent, the mountains around Cooke City. While not likely, human-triggered avalanches could break 2-3 feet deep and over one hundred feet wide on buried weak layers. This weekend, a natural avalanche broke on this layer in the Sheep Creek drainage (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/images/25/natural-avalanche-north-cooke-cit…;), and my partner and I noted the issue in several snowpack assessments over the last two days around Cooke City (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/images/25/ectp18-absarokas"><span><span><sp…;, </span></span></span></span></span></span><a href="https://www.youtube.com/watch?v=t7oJF2TPrXI&amp;list=PLXu5151nmAvToI_ir…;, </span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/34732"><span><span><span><strong><span…;). Saturday and Wednesday of last week, snowmobilers triggered avalanches in the Taylor Fork that broke several feet deep (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/34722"><span><span><span><strong><span…;, </span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/34697"><span><span><span><strong><span…;). Reduce your vulnerability by selecting smaller, less consequential slopes with fewer terrain traps and by following safe travel practices. Digging and testing the snowpack increases your chances of catching critical instability before it catches you.&nbsp;</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>Human-triggered avalanches are possible, and the danger is rated MODERATE across the forecast area. </span></span></span></span></span></span></p>

Natural Avalanche on the Fin

The Fin
Cooke City
Code
SS-N-R2-D2-I
Elevation
10000
Aspect
E
Latitude
45.00460
Longitude
-109.95800
Notes

We noted one avalanche on the Fin that likely occurred yesterday or early this morning from a wind slab or cornice fall. 

Number of slides
1
Number caught
0
Number buried
0
Avalanche Type
Soft slab avalanche
Trigger
Natural trigger
R size
2
D size
2
Bed Surface
I - Interface between new and old snow
Problem Type
Wind-Drifted Snow
Vertical Fall
800ft
Snow Observation Source
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Single Avalanche
Advisory Year

Wind slabs today, wet snow tomorrow

Date
Activity
Snowmobiling

Today, Dave and I did the full mechanized boundary tour north of Cooke City. We rode up and over Daisy Pass towards Wolverine Pass and Mount Abundance, up Lulu Pass, to the Goose Lake boundary, and back out through Round Lake.

In thirty miles of riding, we noted one avalanche on the Fin that likely occurred yesterday or early this morning from a wind slab or cornice fall. That being said, low cloud cover obscured views and the light was relatively flat all day. What was visible were strong winds transporting snow, especially at high elevations. We chose to stay out of steep upper elevation bowls that are regularly wind loaded and out from under corniced ridgelines. 

As we rode, we dug a few snowpits looking for the weak layer that we found yesterday buried about 2 feet deep. While we were able to find this layer, we only got propagation in one of three tests (ECTP 26, E aspect, 9070'). 

Throughout the day, the snow surface became denser and denser. The little precipitation that fell was noticeably rimed and when we rode back into Cooke City around 1pm it was nearly 40 degrees in town. Driving out of Cooke and into the Lamar Valley, we saw a good number of wet loose avalanches breaking in steep, cliffy terrain just south of the road. 

Looking ahead, we are preparing for a sudden shift in the weather with above-freezing temperatures into the alpine and direct sunshine. We are keeping an eye on wind slab avalanches at upper elevations, but will start to shift our focus towards the potential for wet snow avalanche problems in the coming days. 

Region
Cooke City
Location (from list)
COOKE CITY
Observer Name
Darby and Zinn

Slid on Fin in Cooke

Date
Activity
Skiing

Fin had a slide on it today. I was too cloudy to tell if it was released naturally or not.

Region
Cooke City
Location (from list)
Mt Republic
Observer Name
Cascade Tuholske