24-25

Small PWL Avalanche in First Yellow Mule

Buck Ridge
Northern Madison
Code
SS-AMu-R1-D1-O
Elevation
9000
Aspect
N
Latitude
45.17190
Longitude
-111.38000
Notes

In nearly 45 miles of riding, we noted two avalanches. Both breaking on persistent weak layers a few feet down in the snowpack. The first was a small north-facing pocket in the First Yellow Mule (R1-D1) that was snowmobile triggered. It looked to be around a week old. The second was a larger avalanche (R3-D2), east-facing, deep in Muddy Creek. This was drifted in and likely broke around 2.5 weeks ago during the last significant storm cycle.

Number of slides
1
Number caught
0
Number buried
0
Avalanche Type
Soft slab avalanche
Trigger
Snowmobile
Trigger Modifier
u-An unintentional release
R size
1
D size
1
Bed Surface
O - Old snow
Problem Type
Persistent Weak Layer
Slab Thickness
18.0 inches
Vertical Fall
20ft
Slab Width
20.00ft
Images
R1-D1 PWL Avalanche, N facing
Snow Observation Source
Low Danger in the N Madisons
Slab Thickness units
inches
Single / Multiple / Red Flag
Single Avalanche
Advisory Year
24-25

Low Danger in the N Madisons

Date
Activity
Snowmobiling

We rode along Buck Ridge, dropping into First, Second and Third Yellow Mules. We looked into Bear Creek and McAtee Basin drainages before riding through Muddy Creek to the Yellowstone Club boundary. Throughout our ride, we noted tracks nearly everywhere, including many steep slopes. 

In nearly 45 miles of riding, we noted two avalanches. Both breaking on persistent weak layers a few feet down in the snowpack. The first was a small north-facing pocket in the First Yellow Mule (R1-D1) that was snowmobile triggered. It looked to be around a week old. The second was a larger avalanche (R3-D2), east-facing, deep in Muddy Creek. This was drifted in and likely broke around 2.5 weeks ago during the last significant storm cycle. We dug a snowpit near the lower flank of the path and noted that these weak layers had gained strength over time. We did get propagation on a stout melt-freeze crust near the surface (ECTP5) but did not get propagation lower down on faceted grains. 

Currently, these two PWL avalanches are the only PWL avalanches we have seen/have been reported to us in this area this season. This zone seems to be the northernmost extent of the PWL problem that we are dealing with further south in Lionhead, S. Madisons and S. Gallatins. 

Outside of these older two avalanches, we noted no other signs of instability and had a great day of riding. 

Region
Northern Madison
Location (from list)
Buck Ridge
Observer Name
H. Darby

Pit near Zimmer Creek

Date
Activity
Skiing

Dug a pit at 9650ft on a 20° NE facing slope near Zimmer Creek. HS 210-230. ECTN14 at about 40cm down.  

Region
Cooke City
Location (from list)
Zimmer Creek
Observer Name
N Mattes

GNFAC Avalanche Forecast for Tue Mar 4, 2025

Snowpack and Avalanche Discussion

<p>The mountains around West Yellowstone and Cooke City, including the Southern Madison and Southern Gallatin Ranges, have gone a week without significant snowfall but only three days without a significant avalanche (<a href="https://www.mtavalanche.com/node/34421"><span>Lionhead photos and observation</span></a>). Today, the primary concern is<strong> persistent slab avalanches</strong> failing on weak layers buried 2-3 feet deep and breaking up to 200 feet wide. Instability on these layers is the most pronounced in the Lionhead area and Southern Gallatin and Southern Madison Ranges, with mid-elevation, non-wind-loaded terrain being the most likely trigger points. In the last two weeks, backcountry riders triggered many avalanches with several burials and close calls (<a href="https://www.mtavalanche.com/node/34413"><span>Thursday in Cabin Creek</span></a>, <a href="https://www.mtavalanche.com/node/34368"><span>last Monday in Cooke</span></a>, last weekend in <a href="https://www.mtavalanche.com/node/34341"><span>Tepee Basin 1</span></a>, <a href="https://www.mtavalanche.com/node/34301"><span>Tepee Basin 2</span></a>, <a href="https://www.mtavalanche.com/node/34367"><span>Cooke City</span></a>, <a href="https://www.mtavalanche.com/node/34327"><span>Taylor Fork</span></a>, and <a href="https://www.youtube.com/watch?v=tAiSHSEDJhY"><span>Lionhead two Wednesdays ago</span></a>).</p>

<p>The odds of triggering an avalanche decrease each day without new snow, but my trust is hard-earned regarding these weak layers buried like active mines on some slopes and inactive ones on many others.</p>

<p><strong>Travel Advice:</strong> If you plan to play on slopes steeper than 30 degrees, dig and test for instability. To reduce the consequences of an avalanche, choose slopes with fewer terrain traps, such as trees, cliffs, and gullies. Follow safe travel practices and be ready for an avalanche rescue by carrying and training with beacons, shovels and probes.</p>

<p><span>The avalanche danger is rated MODERATE.<span>&nbsp; </span></span></p>

<p>Several inches of new snow in the mountains around Bozeman and 1-2” near Big Sky do not significantly change the avalanche danger. Snow showers are forecast to end soon without much more accumulation, and slides today will generally be shallow, isolated to <strong>loose snow avalanches </strong>or sluffs in steeper terrain and small <strong>wind slab avalanches</strong> where the snow is drifted. Recognize potential instability by noting shooting cracks and deeper drifts.<span>&nbsp; </span></p>

<p>As I discussed in my <a href="https://youtube.com/shorts/dmVA7qCtspA?feature=share"><span>video</span…; from the northern Bridger Range yesterday, after backing off our targeted run, many things need to come together to consider steeper and committing backcountry objectives more safely. While most avalanche terrain remains generally stable, a few inches of new snow rewrites the equation in very steep and extreme terrain where small avalanches can have big consequences.</p>

<p>The avalanche danger is LOW.<span>&nbsp; </span></p>

<p>Avalanches are unlikely in the Centennial Mountains in Island Park. Without recent snow, conditions are generally safe. As I discussed in my <a href="https://youtube.com/shorts/dmVA7qCtspA?feature=share"><span>video</span…; from the Bridger Range yesterday, many things need to line up to consider steep and committing backcountry objectives, including avalanche conditions, snow surface conditions, visibility and partners with the right gear and training. For now, the avalanche conditions component is lined up well. A snowstorm favoring the mountains in Island Park will begin on Thursday, improving riding conditions and increasing the avalanche danger.</p>

<p>Follow standard safe travel protocols and be cautious traveling above or below cornices that can break unexpectedly far back from their edge.</p>

<p><span>The avalanche danger is LOW.<span>&nbsp;</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

Every weekend in Cooke City: Friday at The Antlers at 7 p.m., Free Avalanche Awareness and Current Conditions talk, and Saturday from 10 a.m.-2 p.m. at Round Lake Warming Hut, Free Rescue Practice.

Snow Stability Isnt Everything

Date
Activity
Skiing

Skies were still blue with increasing clouds when we rode up into Fairy Lake zone this morning. We popped up onto the Frazier Basin ridgeline and could see many tracks from skiers over the weekend. As we descended back to Fairy Lake and transitioned to skis, the cloud deck increased and the ceiling lowered. We ascended up Nayu Nuki's east shoulder and at times visibility was limited to 25' in front of our ski tips. Temps were still quite warm and winds were minimal. 

Snow surfaces were variable with a mix of sun crusts, wind board, and in shallower tree-sheltered zones, sugary faceted snow. It will be interesting to see how well a few inches of new snow this week bonds with these different snow surfaces. 

While our original trip plan involved stepping out into steeper avalanche terrain, we decided to pull the plug due to extremely limited visibility. This was an example of how even though avalanche conditions may be generally stable, there are other factors to consider when choosing to ski steeper lines (visibility of your partners, visibility of surrounding avalanche terrain, etc.) 

Region
Bridger Range
Location (from list)
Fairy Lake
Observer Name
H. Darby
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