24-25

GNFAC Avalanche Forecast for Sat Mar 15, 2025

Snowpack and Avalanche Discussion

<p><span><span><span><span><span><span>Avalanches involving the recent snow are possible for a person to trigger. The main concern is </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>breaking 6 inches to 2 feet deep where the new snow is drifted into thicker or stiffer slabs. Yesterday the wind was calm, so if the wind increases today there is still plenty of soft snow to be drifted into fresh, reactive wind slabs.</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>Yesterday, near Cooke City there were a handful of small avalanches (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/34584"><span><span><span><strong><span…;), and in the Centennials near Island Park Mark saw a larger avalanche that broke on or under a crust below the new snow (</span></span></span></span></span></span><a href="https://www.youtube.com/watch?v=3ziK29iO3zQ&amp;list=PLXu5151nmAvToI_ir…;). These occurred where there was just the slightest bit of wind to stiffen the snow surface. Avoid wind-loaded slopes near ridgelines to minimize the chances of triggering an avalanche. Watch for snow blowing off ridges, and look for cracking around your skis as signs of fresh wind slabs.</span></span></span></span></span></span></p>

<p><span><span><span><strong><span><span>Loose snow avalanches, </span></span></strong></span></span></span><span><span><span><span><span><span>dry or wet, are also possible and can easily run long distances on the crust below the new snow (</span></span></span></span></span></span><a href="https://www.youtube.com/watch?v=6pLrdFVFpdE&amp;list=PLXu5151nmAvToI_ir…;. These will be small and somewhat predictable, but could be dangerous if they drag you into rocks, trees or over a cliff. If the sun shines it may quickly soften the snow surface and increase the chance of wet loose slides on sunny slopes.</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>In the southern Madison and southern Gallatin ranges and near West Yellowstone, the weak snow that was buried in late January can produce deeper </span></span></span></span></span></span><span><span><span><strong><span><span>persistent slab avalanches</span></span></strong></span></span></span><span><span><span><span><span><span>. <strong>Yesterday in the Taylor Fork a snowmobiler triggered a 4 foot deep slide in an isolated short, steep pocket of snow</strong> (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/34599"><span><span><span><strong><span… and observation</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>). This underscores the importance of only exposing one person at a time to steep slopes, and carrying proper avalanche rescue gear (transceiver, shovel and probe). These types of slides have become increasingly less frequent, but we could see more with the added weight of new snow over the next few days.</span></span></span></span></span></span></p>

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

Snowmobiler triggered 3 foot deep slide Sunlight Basin

Taylor Fork
Southern Madison
Code
HS-AMu-R2-D2-O
Elevation
8800
Aspect
NW
Latitude
44.97720
Longitude
-111.28600
Notes

A group of riders saw Mark at the gas station and shared that they had triggered a 4' deep slide in a small pocket in Sunlight Basin of the Taylor Fork area. It was in an area with a relatively shallower snowpack, and broke on weak snow near the bottom of the snowpack. The rider that triggered it was going uphill and got stuck shortly after and noted the snowpack was much deeper there.

Number of slides
1
Number caught
0
Number buried
0
Avalanche Type
Hard slab avalanche
Trigger
Snowmobile
Trigger Modifier
u-An unintentional release
R size
2
D size
2
Bed Surface
O - Old snow
Problem Type
Persistent Slab
Slab Thickness
36.0 inches
Vertical Fall
100ft
Slab Width
50.00ft
Slab Thickness units
inches
Single / Multiple / Red Flag
Single Avalanche
Advisory Year

On Mar 14 A group of riders shared that they had triggered a 4' deep slide in a small pocket in Sunlight Basin of the Taylor Fork area. It was in an area with a relatively shallower snowpack, and broke on weak snow near the bottom of the snowpack. The rider that triggered it was going uphill and got stuck shortly after and noted the snowpack was much deeper there.

Southern Madison, 2025-03-15

Snowmobiler triggered 4 foot deep slide Sunlight Basin

Date
Activity
Snowmobiling

A group of riders saw Mark at the gas station and shared that they had triggered a 4' deep slide in a small pocket in Sunlight Basin of the Taylor Fork area. It was in an area with a relatively shallower snowpack, and broke on weak snow near the bottom of the snowpack. The rider that triggered it was going uphill and got stuck shortly after and noted the snowpack was much deeper there.

Region
Southern Madison
Location (from list)
Taylor Fork

small dry loose slides north of Cooke

Crown Butte
Cooke City
Code
L-N-R1-D1-S
Elevation
9500
Aspect
S
Aspect Range
S, NE
Latitude
45.05250
Longitude
-109.96200
Notes

There was a small natural dry loose on south face of Crown Butte and I triggered a dry loose slide on a test slope near the ridge on Miller ridge (video).

Number of slides
2
Number caught
0
Number buried
0
Avalanche Type
Loose-snow avalanche
Trigger
Natural trigger
R size
1
D size
1
Bed Surface
S - Avalanche released within new snow
Problem Type
Loose Dry
Slab Thickness
5.0 inches
Slab Thickness units
inches
Single / Multiple / Red Flag
Multiple Avalanches
Advisory Year

Dug a pit on a northeast facing slope, 9300' (profile and pic attached) near Cooke City. Snow depth was 7-8 feet. 6" of new snow was right side up. Below the new snow was a soft (1F-) melt-freeze crust with soft decomposing and slightly faceted particles below. ECTN13 broke below the crust. Below that the snowpack was 1F to P+ hard and lacked weak layers. The Feb 4 dirt layer was clearly visible. Photo: GNFAC

Cooke City, 2025-03-14