24-25

Small snowmobile triggered avalanche in Taylor Fork

Date
Activity
Snowmobiling

From text message: a snowmobile triggered a small persistent slab avalanche in the Taylor Fork on Tuesday. The rider was not caught. 

On a nearby slope, a larger avalanche failed 150 wide on weak layers near the ground. 

Region
Southern Madison
Location (from list)
Taylor Fork
Observer Name
Omar El-Zaru

Large storm slab avalanches in North Bridgers

Northern Bridgers
Bridger Range
Code
SS-N-R2-D2-S
Elevation
7800
Aspect Range
E
Latitude
45.87420
Longitude
-110.95100
Notes

We went out today and saw the crown of this avalanche around 2-3pm. Looked quite fresh.

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
S - Avalanche released within new snow
Problem Type
Storm Slab
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Single Avalanche
Advisory Year

Large storm slab avalanches in North Bridgers

Date
Activity
Skiing

From Instagram story tag: there were many large storm slab avalanches in the northern Bridgers on Monday and Tuesday during the avalanche warning. 

Region
Bridger Range
Location (from list)
Northern Bridgers
Observer Name
Chris Kussmaul

Remotely Triggered slides in Portal Creek

Date
Activity
Snowmobiling

Around 7 p.m. Monday night, a few miles up Portal Creek, triggered from bottom of slope.

Region
Northern Gallatin
Location (from list)
Portal Creek
Observer Name
P. Costain via IG

GNFAC Avalanche Forecast for Wed Jan 1, 2025

Snowpack and Avalanche Discussion

<p><span><span><span><strong><span><span>3-day storm total</span></span></strong></span></span></span><span><span><span><span><span><span> for the Bridger Range is </span></span></span></span></span></span><span><span><span><strong><span><span>34.75 inches of snow (2.45 inches of SWE)</span></span></strong></span></span></span><span><span><span><span><span><span>. There is simply a lot of new snow that added a lot of weight and STRESS to the snowpack which needs time to adjust to this rapid change. How much weight? The new snow over an area the size of a football field weighs over 600,000 pounds.</span></span></span></span></span></span></p>

<p><span><span><span><strong><span><span>During the storm</span></span></strong></span></span></span><span><span><span><span><span><span> there were many storm slab avalanches breaking within the new snow including one that caught and carried a skier in </span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/33144"><span><span><span><span><span><… Meadow on Monday</span></span></u></span></span></span></span></span></a><span><span><span><span><span><span>. There easily could have been bigger avalanches but they would have been hard to see due to heavy snowfall and poor visibility.&nbsp;</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>In the long run, the snowpack will become stronger (</span></span></span></span></span></span><a href="https://www.youtube.com/watch?v=ogI1xknwVBM"><span><span><span><span><s…’s video from yesterday</span></span></u></span></span></span></span></span></a><span><span><span><span><span><span>), but today I would not be surprised to hear of a </span></span></span></span></span></span><span><span><span><strong><span><span>large persistent slab avalanche</span></span></strong></span></span></span><span><span><span><span><span><span>. I’m unsure of the likelihood of triggering a slide, but I am sure that for today these are </span></span></span></span></span></span><span><span><span><strong><span><span>dangerous avalanche conditions</span></span></strong></span></span></span><span><span><span><span><span><span> and the danger is CONSIDERABLE.</span></span></span></span></span></span></p>

<p><span><span><span><strong><span><span>Storm Totals from the Last Week:&nbsp;</span></span></strong></span></span></span></p>

<ul>
<li><span><span><span><span><span><span>Cooke City, Island Park and S. Madison Range: 22-25” of snow (2.5-2.9” SWE)</span></span></span></span></span></span></li>
<li><span><span><span><span><span><span>Lionhead, Northern Madison and Northern Gallatin Range: 21-25” of snow (1.8-2.4” SWE)</span></span></span></span></span></span></li>
</ul>

<p><span><span><span><strong><span><span>Persistent slab avalanches </span></span></strong></span></span></span><span><span><span><span><span><span>failing on buried weak layers 1-3 feet deep (deeper on wind-loaded slopes) are the main problem today. Two good examples from Monday are a natural avalanche near West Yellowstone </span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/33148"><span><span><span><span><span><… Quake Lake</span></span></u></span></span></span></span></span></a><span><span><span><span><span><span>&nbsp;and another on Henderson Mtn. near Cooke City (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/33139"><span><span><span><span><span><… report</span></span></u></span></span></span></span></span></a><span><span><span><span><span><span> and </span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/33160"><span><span><span><span><span><… profile</span></span></u></span></span></span></span></span></a><span><span><span><span><span><span>). Scroll through </span></span></span></span></span></span><a href="https://www.mtavalanche.com/snow-observations-list"><span><span><span><… observations</span></span></u></span></span></span></span></span></a><span><span><span><span><span><span> to see other avalanches and reports.</span></span></span></span></span></span></p>

<p><span><span><span><strong><span><span>Heads up</span></span></strong></span></span></span><span><span><span><span><span><span> - Increased winds this morning transporting snow as well as possible heavy snowfall mostly near Island Park and West Yellowstone will add to the danger. The most dangerous conditions are often the result of winds more than snowfall alone.</span></span></span></span></span></span></p>

<p><span><span><span><strong><span><span>What to do?</span></span></strong></span></span></span><span><span><span><span><span><span> Conditions aren’t super sensitive which can lull you into a false sense of security because you may not immediately see signs of instability. I fell into this trap yesterday on Sawtelle Peak near Island Park, but then Ian and I walked across several southerly facing, low-angle slopes and </span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/33167"><span><span><span><span><span><… about 4 rumbling collapses</span></span></u></span></span></span></span></span></a><span><span><span><span><span><span>. I’m optimistic about stability improving in the future but </span></span></span></span></span></span><span><span><span><strong><span><span>remain skeptical for now</span></span></strong></span></span></span><span><span><span><span><span><span>. The safest option is to ride slopes less than 30 degrees in steepness. The most dangerous choice and the most likely places to trigger an avalanche are slopes steeper than 30 degrees near and above treeline loaded by current or previous winds.</span></span></span></span></span></span></p>

<p><span><span><span><strong><span><span>Be cautious and conservative today</span></span></strong></span></span></span><span><span><span><span><span><span> because avalanche conditions are dangerous and the danger is CONSIDERABLE. </span></span></span></span></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