N45.923090° W110.958035°
8150ft NE aspect 20 degree slope
ECT18 at 20cm boundary between soft slab and depth hoar. All "sugar" below the boundary extending to the ground. No releases were observed. In the distance at far northern peaks there were cornices that had released naturally.
We rode into the Throne in the northern Bridgers. On the east facing hill visible from the sleds, a slab avalanche about 1 foot deep and 100 feet wide was seen. The debris fanned out and did not seem deep enough to bury a person. A roller ball likely triggered it on Sunday (01/21/24) as there were no roller ball tracks on the bed surface, only leading to the crown. It was a bit disheartening to think that a roller ball was enough to trigger a slide.
We skinned to the runout zone of the Throne letting our runout angle approach 23 degrees. We has numerous collapses and we decided to not ascent because there is not a way to stay out of avalanche terrain, plus we were concerned about having a collapse propagate up the hill and avalanche on us.
We rode into the Throne in the northern Bridgers. On the east facing hill visible from the sleds, a slab avalanche about 1 foot deep and 100 feet wide was seen. The debris fanned out and did not seem deep enough to bury a person. A roller ball likely triggered it on Sunday (01/21/24) as there were no roller ball tracks on the bed surface, only leading to the crown. It was a bit disheartening to think that a roller ball was enough to trigger a slide.
We skinned to the runout zone of the Throne letting our runout angle approach 23 degrees. We has numerous collapses and we decided to not ascent because there is not a way to stay out of avalanche terrain, plus we were concerned about having a collapse propagate up the hill and avalanche on us.
Large natural avalanches and significant cornice formation were visible in October Bowl.
Large natural avalanches and significant cornice formation were visible in October Bowl. We noted frequent collapsing and shooting cracks (5-100ft+) on E facing slopes at ~8000ft.
Photo taken 1/30/24
Skiers near Fairy Lake saw large natural avalanches and significant cornice formation in October Bowl and triggered this large shooting crack. Photo: M. Yzaguirre
Large natural avalanches and significant cornice formation were visible in October Bowl. We noted frequent collapsing and shooting cracks (5-100ft+) on E facing slopes at ~8000ft.
<p>Human-triggered avalanches are very likely on all steep slopes in Island Park. New snow is overloading an exceptionally weak snowpack. Avoid avalanche terrain and avalanche runout zones.</p>
<p>The Centennial Mountains have received a foot or more of snow since Saturday, equal to 1.2” of snow water equivalent. While this is a <em>normal<span> amount of snow</span></em>, it fell onto an <em>abnormally weak<span> snowpack</span></em>. Riders and skiers are triggering avalanches from long distances away from flat terrain and seeing shooting cracks extend hundreds of feet ahead (<a href="https://www.mtavalanche.com/snow-observations-list"><strong><span>obser…;). As the director of the Utah Avalanche Center said last week from Island Park, “Head’s up. We’re seeing avalanches. It is a good sign that there will be more” (<a href="https://www.youtube.com/watch?v=LzkWoa4viY0"><strong><span>video</span>…;
<p><span>Today, give yourself a wide margin for error and avoid recreating on slopes close to the 30-degree threshold we use to describe avalanche terrain. The avalanche danger is rated <span>HIGH</span> on all slopes. </span></p>
<p>The loading from new snow has slowed south of Big Sky and near West Yellowstone and Cooke City. However, human-triggered avalanches breaking 1-2 feet deep are very likely, especially on slopes loaded by wind-drifted snow. <em>Stability will improve unusually slowly</em> in the absence of additional snow and wind-loading <em>due to unusually fragile persistent weak layers</em> buried within the snowpack.</p>
<p>Backcountry travelers submitted dozens of reports of avalanches, shooting cracks and collapsing (<a href="https://www.mtavalanche.com/avalanche-activity"><strong><span>avalanche activity log</span></strong></a>). On Sunday in the Lionhead area, Alex and I barely stepped off our sleds when we triggered our first collapse, shooting cracks and saw a natural avalanche (<a href="https://www.youtube.com/watch?v=mSked07bAY8&lc=UgwOJBQp1Ujv-9h17St4…;). Ian and his partner triggered an avalanche from a low-angle slope 800 feet away in Cooke City last week (<a href="https://www.youtube.com/watch?v=74rb5HCvbsE"><strong><span>video</span>…;
<p>Signs of instability do not get clearer. Give yourself wide margins for safety by recreating in terrain less than 30 degrees steepness and avoiding avalanche terrain. The avalanche danger is HIGH on wind-loaded slopes and CONSIDERABLE on all others.</p>
<p>Human-triggered avalanches breaking 1-2 feet deep are likely in the mountains around Bozeman and Big Sky. Conservative terrain selection answers the problem of dangerous avalanche conditions stemming from persistent weak layers. Slopes under 30 degrees steepness are unlikely to slide if not connected to steeper terrain.</p>
<p>Yesterday, in the mountains near Big Sky, I triggered an avalanche that failed on a steep slope while I was 750 feet away in a flat meadow (<a href="https://youtu.be/jDOAJ1yGmGk"><strong><span>video</span></strong></a>). We received reports of similar experiences on <a href="https://www.mtavalanche.com/node/30123"><strong><span>Flanders Mountain</span></strong></a><u><span> </span></u><span>and</span> <a href="https://www.mtavalanche.com/node/30129"><strong><span>Hyalite Peak</span></strong></a>. On Sunday, a skier descending Saddle Peak triggered a slab that broke 2-3 feet deep, ultimately propagating 500 feet wide and running over 1000 vertical feet (<a href="https://www.mtavalanche.com/node/30161"><strong><span>details and photos</span></strong></a>). The <a href="https://www.mtavalanche.com/avalanche-activity"><strong><span>avalanche activity log</span></strong></a> is packed with recent slides. Thankfully, no one has been caught or injured. Let’s keep it that way.</p>
<p>The avalanche danger is rated CONSIDERABLE. Cautious route-finding, thorough snowpack assessment and conservative decision-making are essential.</p>
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.
AVALANCHE WARNING: Island Park
