24-25

Wet Loose Avalanches Cooke City

Hayden Creek
Cooke City
Code
WL-NC-R1-D1-S
Elevation
10000
Aspect
E
Latitude
44.99520
Longitude
-109.90800
Notes

While touring south of town today, we observed two D1 wet loose avalanches on an east aspect at 10000’. Both occurred at 11am and were triggered by a small cornice fall due to rapid warming.

Number of slides
2
Number caught
0
Number buried
0
Avalanche Type
Wet loose-snow avalanche
Trigger
Cornice fall
R size
1
D size
1
Bed Surface
S - Avalanche released within new snow
Problem Type
Loose Wet
Snow Observation Source
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Multiple Avalanches
Advisory Year

Wet Loose Avalanches Cooke City

Date
Activity
Skiing

While touring south of town today, we observed two D1 wet loose avalanches on an east aspect at 10000’. Both occurred at 11am and were triggered by a small cornice fall due to rapid warming.

Region
Cooke City
Location (from list)
Hayden Creek
Observer Name
Nina Hance

Skier caught and carried on Cowen

Date
Activity
Skiing

Party of 3 skiers triggered a wind slab about 500 feet below the entrance to Moe's Gullies, just south of Mount Cowen. Skier 1 ski cut the entrance to the couloir, with no visible effect. Skiers 1, 2, and 3 then one by one skied down about 200 feet before cutting into the skiers right gully. This was also skied one at a time, after which they regrouped about 500 feet below the entrance/ridge. Skier 1 then traversed out so ski the apron, and triggered a D1 avalanche on a wind slab which broke about 100 feet above. Crown is estimated to be about 20" at the deepest, and was at the transition point between the choke of the parallel gully and the apron below. Skier 1 was carried about 200 feet before being able to self arrest. Skiers 2 and 3 were in a safe spot and not caught. Avalanche ran the full length of the path, and triggered sympathetic avalanches on the way down. This created a relatively large debris pile compared to the size of the initial release. Avalanche seemed comprised mostly of the last storm snow running on a hard crust below. 

 

No injuries were sustained.

Region
Out of Advisory Area
Observer Name
Jonas David

test scores

Date
Activity
Skiing
Region
Cooke City
Observer Name
Test observation

GNFAC Avalanche Forecast for Sun Apr 6, 2025

Snowpack and Avalanche Discussion

<p><span><span><span><span><span><span>Today the two main avalanche problems you might encounter are </span></span></span></span></span></span><span><span><span><strong><span><span>wind slab avalanches</span></span></strong></span></span></span><span><span><span><span><span><span> and </span></span></span></span></span></span><span><span><span><strong><span><span>wet loose avalanches</span></span></strong></span></span></span><span><span><span><span><span><span>. Yesterday in the Bridger Range, wind slab avalanches were triggered by skiers (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/34844"><span><span><span><strong><span… Peak</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>, </span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/34845"><span><span><span><strong><span… Great One</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>), and some loose snow avalanches ran naturally (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/images/25/natural-loose-slides-bridge-ridge…;). I had similar </span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/34848"><span><span><span><strong><span…; near Cooke City where wind slabs were notably more reactive than expected, despite having had some time to stabilize since snowfall tapered off a couple days ago.</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>Don’t trust old drifts today, and expect any fresh drifts to be easy to trigger. These wind slabs are relatively small, but can easily knock you over and be harmful if they carry you into rocks, over a cliff, or down a long steep slope. A textured or rounded snow surface is a sign the snow has been drifted into a stiffer slab. Be cautious of wind-loaded slopes, especially in terrain where being carried in even a small slide would have high consequences.</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>As sunshine and above freezing temperatures melt the snow surface, wet loose avalanches will become possible to trigger and some may run naturally. Soft snow from last week is sitting on firm crusts which could cause wet loose slides to be pretty big and run far. Temperatures are starting warmer and will be higher than yesterday which will probably cause the snowpack to lose strength earlier in the day, and get wet deeper into the snowpack and on slopes that remained dry yesterday.</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>Expect the snow surface to get weaker through the day, especially on slopes that receive direct sunshine. Sunny slopes will have a crust this morning. Plan to be off steep slopes before the crust melts or the surface gets wet. Moist sticky snow or roller-balls on the surface mean it is time to find lower angle terrain or slopes with colder, dry snow on the surface.</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>The sunshine and heat will also make </span></span></span></span></span></span><span><span><span><strong><span><span>cornice falls</span></span></strong></span></span></span><span><span><span><span><span><span> possible. Along ridgelines, overhanging drifts of snow have become large. As these cornices melt and lose strength they could break naturally or under the weight of a person. Minimize your time on slopes below cornices and stay far back from the edge while travelling on ridgelines above them.</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>The avalanche danger is MODERATE across the forecast area.</span></span></span></span></span></span></p>

natural loose snow slides in Bridgers

Bridger Peak
Bridger Range
Code
L-N-R1-D1.5
Elevation
8500
Aspect
E
Latitude
45.77010
Longitude
-110.94000
Notes

Observed multiple D1-1.5 natural dry loose avalanches (and some tiny wind slab pockets under the ridge cornice) that likely occurred during peak warming around 2-3 PM. North/sheltered aspects from ~9- 8.5k held an average of 8+ inches of dry, drifted snow. Early AM to mid-afternoon, very active wind transport followed by tapered winds and a rapid increase in temp.

Number caught
0
Number buried
0
Avalanche Type
Loose-snow avalanche
Trigger
Natural trigger
R size
1
D size
1.5
Snow Observation Source
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Multiple Avalanches
Advisory Year

Natural wind slabs and loose snow near Cooke

Henderson Mountain
Cooke City
Code
Latitude
45.05240
Longitude
-109.94500
Notes

We saw a couple 3-6" deep natural wind slab avalanches and a few dry loose slides that looked to have happened within the last 24 hours. On southerly slopes below 9,000' there were some wet loose slides from yesterday afternoon.

Number of slides
4
Number caught
0
Number buried
0
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Multiple Avalanches
Advisory Year

Reactive wind slabs near Cooke City

Henderson Mountain
Cooke City
Code
HS-AS-R1-D1-S
Elevation
9800
Aspect
NE
Latitude
45.05240
Longitude
-109.94500
Notes

Wind slabs were still reactive today. We triggered 3 small, 3-8" deep x 5-15' wide, hard wind (1F+) slabs on convex test slopes well below the main ridgelines. 9,800', NE aspects. Also triggered one softer (4F) wind slab just below the high ridgeline, 10,200', NE aspect. 10-15' wide x 6-8" deep.

Number of slides
4
Number caught
0
Number buried
0
Avalanche Type
Hard slab avalanche
Trigger
Skier
R size
1
D size
1
Bed Surface
S - Avalanche released within new snow
Problem Type
Wind Slab
Slab Thickness
8.0 inches
Vertical Fall
50ft
Slab Width
15.00ft
Slab Thickness units
inches
Single / Multiple / Red Flag
Multiple Avalanches
Advisory Year

Apr 5 Wind slabs were still reactive. We triggered 3 small, 3-8" deep x 5-15' wide, hard wind (1F+) slabs on convex test slopes well below the main ridgelines. 9,800', NE aspects. Photo: GNFAC

Cooke City, 2025-04-06

Apr 5 Wind slabs were still reactive. We triggered 3 small, 3-8" deep x 5-15' wide, hard wind (1F+) slabs on convex test slopes well below the main ridgelines. 9,800', NE aspects. Also triggered one softer (4F) wind slab just below the high ridgeline, 10,200', NE aspect. 10-15' wide x 6-8" deep (Pictured). Photo: GNFAC

Cooke City, 2025-04-06