24-25

Wind Loading in Ainger Lake Basin

Date
Activity
Snowboarding

Toured into Ainger Lake Basin in the Northern Bridgers today. From the Shafthouse Trailhead we could see debris from past wet snow avalanches coming from Ainger Peak and Hard Scrabble Peak area. The slide in Ainger Lake Basin must have been at least a few days old as the slide path and debris were covered in new snow from the last snowfall. The evidence of multiple slides we saw in Ainger Basin looked like they came from rocks shedding snow in the warm weather we've been having. Our objective was the middle couloir on Ainger Headwall. It was very windy in the basin. The slope above Ainger Lake Basin that we had to cross to get to the couloir was heavily wind loaded. We toured up and the snow felt stable so I decided to slowly skin out to see how the snow on this slope felt. It quickly became hollow sounding and we turned around and got a couple laps in for the day from there. Up high in the basin sun baked slopes that froze over night were very slick and hard with a couple inches of new snow on top making skinning difficult in places as well. 

Region
Bridger Range
Location (from list)
Frazier Basin
Observer Name
Connor Culver

GNFAC Avalanche Forecast for Sat Mar 8, 2025

Snowpack and Avalanche Discussion

<p><span><span><span><strong><span><span>Wind Slab avalanches </span></span></strong></span></span></span><span><span><span><span><span><span>breaking in drifts built from this week’s new snow are the </span></span></span></span></span></span><span><span><span><strong><span><span>primary avalanche concern</span></span></strong></span></span></span><span><span><span><span><span><span> today. These drifts are up to 2 ft deep and were easily triggered yesterday (</span></span></span></span></span></span><a href="https://www.youtube.com/watch?v=Y8xb7L0c0Ug"><span><span><span><strong>…;). Drifts may be a little more stubborn today, but I expect there are many slopes where they can still be triggered. Winds on Thursday were out of the east and then shifted westerly yesterday, so drifts may be found in unusual locations. The surface texture of the snow will give you a good idea of where the drifts are. Either avoid these drifts today, or carefully assess and make sure they’re well bonded before getting onto steep slopes.</span></span></span></span></span></span></p>

<p><span><span><span><strong><span><span>Around West Yellowstone, Persistent Slab avalanches are an additional concern</span></span></strong></span></span></span><span><span><span><span><span><span>, breaking deeper on weak layers buried at the end of January. We haven’t seen a ton of activity on these layers lately, but we did get a report of a slide breaking deeper yesterday in the Lionhead area, so they’re clearly still possible (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/images/25/wind-loaded-slide-backside-lionhe…;). These slides have mostly been breaking on mid-elevation slopes with trees around and have been surprising riders, leading to several close calls (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/34421"><span><span><span><span><span><…;, </span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/34413"><span><span><span><span><span><… Creek</span></span></u></span></span></span></span></span></a><span><span><span><span><span><span>). Make sure you’re only exposing one person at a time to steep slopes and have a partner watching from a safe spot, in case you get unlucky and trigger a deeper slide.</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>Expect small</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>as the new snow warms up in the strong March sun. These slides could break at your feet or sled or come down naturally from above, particularly around rock outcrops. These slides probably won’t be big enough to bury you, but could knock you off your feet, so be alert in terrain where that would be a problem.</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>The avalanche danger is MODERATE today.</span></span></span></span></span></span></p>

<p><span><span><span><strong><span><span>Winds Slab</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>are also the primary concerns near Cooke City, but they will be small and isolated today. </span></span></span></span></span></span><span><span><span><strong><span><span>The snowpack is generally stable.</span></span></strong></span></span></span><span><span><span><span><span><span> There are weak layers in the snowpack, but it’s been almost two weeks since the last slide on them (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/34382"><span><span><span><span><span><…;).&nbsp;</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>Stay alert so you don’t get surprised. Watch for cracking as a sign that a wind drift is unstable and pay attention as the snow surface gets wet, especially in very steep terrain where a tiny slide would have big consequences.</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>Large avalanches are unlikely and the avalanche danger is LOW.</span></span></span></span></span></span></p>

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Loose avalanches on Blackmore

Mt Blackmore
Northern Gallatin
Code
N-R1-D1
Latitude
45.44440
Longitude
-111.00400
Notes

From obs: "Multiple natural loose avalanches in the steep terrain of mt Blackmore. All originated at the base of cliffs or trees. Counted 4 prominent ones"

Number of slides
4
Number caught
0
Number buried
0
Trigger
Natural trigger
R size
1
D size
1
Snow Observation Source
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Multiple Avalanches
Advisory Year

Natural Persistent Slab at Lionhead

LIONHEAD AREA
Lionhead Range
Code
HS-N-R3-D2
Latitude
44.74510
Longitude
-111.38800
Notes

From obs: "Looks like a recent naturally triggered slide towards the Idaho wilderness boundary on lionhead."

Number of slides
1
Number caught
0
Number buried
0
Avalanche Type
Hard slab avalanche
Trigger
Natural trigger
R size
3
D size
2
Slab Thickness
48.0 inches
Vertical Fall
100ft
Slab Width
100.00ft
Slab Thickness units
inches
Single / Multiple / Red Flag
Single Avalanche
Advisory Year

Mar 7 obs: "...There was 6" of low density snow from yesterday. Winds were stronger than expected, from the north at the top of the Throne, and increased through the morning.... We found fresh drifts that were reactive, cracking easily and 5-10' wide out from our skis, on south and east facing slopes around 8000-8300'." Photo: GNFAC

Bridger Range, 2025-03-07

Mar 7 obs: "...There was 6" of low density snow from yesterday. Winds were stronger than expected, from the north at the top of the Throne, and increased through the morning.... We found fresh drifts that were reactive, cracking easily and 5-10' wide out from our skis, on south and east facing slopes around 8000-8300'." Photo: GNFAC

Bridger Range, 2025-03-07