Saw a group of skiers trigger a small wind slab avalanche on an eastern aspect at around 8,300' in the main fork of Hyalite in "Candy Land" just south of the climb Big League Chew at 2:00pm on Saturday (11/26). Crown looked to be around 2" to 1' and 90' wide. The slide ran maybe 100'. No skiers were caught. Photo: Anon
Saw a group of skiers trigger a small wind slab avalanche on an eastern aspect at around 8,300' in the main fork of Hyalite in "Candy Land" just south of the climb Big League Chew at 2:00pm on Saturday (11/26). Crown looked to be around 2" to 1' and 90' wide. The slide ran maybe 100'. No skiers were caught. Photo: Anon.
Saw a group of skiers trigger a small wind slab avalanche on an eastern aspect at around 8,300' in the main fork of Hyalite in "Candy Land" just south of the climb Big League Chew at 2:00pm on Saturday (11/26). Crown looked to be around 2" to 1' and 90' wide. The slide ran maybe 100'. No skiers were caught. It was triggered as the first skier traversed out onto the intended ski line from the trees which they skinned up. The fracture extended from the tips of the first skiers skis and ran across the slope and underneath a small cliff band. The group skied out on a slightly lower angle slope adjacent to the slide. My group watched from below an adjacent ski run approximately 300 yards away as the slide happened. We had dug a pit on a similar aspect in the area approximately 30 minutes before the slide and found 85cm of snow with a weak layer at 42-45cm which failed CTs but we couldn't get propagation. (CT22, ECTN21). It looked like this was probably the layer that failed in this slide.
Saw a group of skiers trigger a small wind slab avalanche on an eastern aspect at around 8,300' in the main fork of Hyalite in "Candy Land" just south of the climb Big League Chew at 2:00pm on Saturday (11/26). Crown looked to be around 2" to 1' and 90' wide. The slide ran maybe 100'. No skiers were caught. It was triggered as the first skier traversed out onto the intended ski line from the trees which they skinned up. The fracture extended from the tips of the first skiers skis and ran across the slope and underneath a small cliff band. The group skied out on a slightly lower angle slope adjacent to the slide. My group watched from below an adjacent ski run approximately 300 yards away as the slide happened. We had dug a pit on a similar aspect in the area approximately 30 minutes before the slide and found 85cm of snow with a weak layer at 42-45cm which failed CTs but we couldn't get propagation. (CT22, ECTN21). It looked like this was probably the layer that failed in this slide.
Toured up to the NE shoulder on Mt. Blackmore yesterday. Winds were strong and variable, but mostly gusting from the S-SW. A lot of snow was moving around, skin tracks were filled in very quickly, and you could actively see small cornices starting to build on the lee side of the ridge.
On the descent, I intentionally triggered a small wind pocket in one of the chutes in the cliffs near the trail at 8700 ft. I included a video. It was D1 and about 5 inches deep at the crown. I think just a good reminder that even in the trees, the tops of those chutes get wind loaded and can definitely slide.
<p>Dangerous avalanche conditions exist in the mountains around West Yellowstone and Cooke City and in the Gallatin and Southern Madison Ranges where, in the last 48 hours, 9-13” of snow fell equal to 0.7-1” of <a href="https://www.nrcs.usda.gov/wps/portal/nrcs/detail/null/?cid=nrcseprd1314… water equivalent</span></a> (SWE). Yesterday, strong winds gusting to 65 mph created unstable drifts at many elevations and aspects. Human-triggered avalanches breaking up to two feet deep are likely on wind-loaded slopes. Larger avalanches breaking deeper into the snowpack are possible.</p>
<p>Smaller slides on steep slopes unaffected by the wind could be large enough to injure or kill riders and skiers, especially where terrain traps like rocks, trees or cliffs enhance the consequences of getting caught in a slide. Watch for signs instability such as recent avalanches, collapsing and cracking that tell us to avoid steep slopes entirely. A snow pit will help test for these new snow instabilities and those lurking deeper in the snowpack.</p>
<p>Today, careful route-finding that avoids steep, wind-loaded slopes, a snowpack assessment focused on identifying instabilities in new and wind-drifted snow along with conservative decision-making are essential. The danger is rated CONSIDERABLE.</p>
<p>In the last 48 hours, the Bridger and Northern Madison Ranges received 7-9” of new snow, equal to 0.5-0.8” of SWE. Strong winds yesterday and the new snow create a heightened avalanche danger, especially on slopes loaded with slabs of wind-drifted snow.</p>
<p>Yesterday, two groups triggered avalanches on wind-loaded slopes within the boundaries of Bridger Bowl (<a href="https://www.mtavalanche.com/node/26959"><strong><span>details and photos incident 1</span></strong></a><strong>, </strong><a href="https://www.mtavalanche.com/node/26961"><strong><span>incident 2</span></strong></a>). These two incidents make four unintentionally triggered avalanches within the boundaries of the closed ski area in the last five days, with one skier carried nearly 150’ (<a href="https://www.mtavalanche.com/node/26929"><strong><span>details and photos</span></strong></a>). During avalanche mitigation work, the Big Sky Ski Patrol triggered numerous avalanches on freshly wind-loaded slopes that broke 12-18” deep. Similar avalanches are possible today.</p>
<p>The Big Sky Ski Patrol triggered one larger slide that failed on deeper weak layers that exist regionally on high-elevation north-facing slopes (<a href="https://www.mtavalanche.com/node/26966"><strong><span>details and photos</span></strong></a>, <a href="https://www.mtavalanche.com/node/26883"><strong><span>Hyalite Peak avalanche</span></strong></a>, <a href="https://www.mtavalanche.com/node/26938"><strong><span>natural avalanche on deeper weak layers at Big Sky</span></strong></a>).</p>
<p>Today, evaluate your terrain choices carefully and assess the snowpack by looking for instabilities in the new and wind-drifted snow. Human-triggered avalanches are possible, and the avalanche danger is MODERATE.</p>
<p>If you get out, please share avalanche, snowpack or weather observations via our <a href="https://www.mtavalanche.com/node/add/snow_obs"><strong><span>website</s…;, email (<a href="mailto:mtavalanche@gmail.com"><strong><span>mtavalanche@gmail.com</span…;), phone (406-587-6984), or Instagram (#gnfacobs).</p>
<p><span><span><span>Dangerous avalanche conditions exist in the mountains near Island Park where 13” of new snow fell in the last 48 hours, and strong winds blew yesterday. Human-triggered avalanches breaking up to two feet deep are likely on wind-loaded slopes. Larger avalanches breaking deeper into the snowpack are possible. Careful route-finding that avoids steep, wind-loaded slopes, a snowpack assessment focused on identifying instability in new and wind-drifted snow and conservative decision-making are essential.</span></span></span></p>
Our education calendar is full of awareness lectures and field courses. Check it out: Events and Education Calendar.
Tuesday, November 29, 6 p.m. Sidecountry Avalanche Awareness for Families (and Friends) at Story Mill Park. Free.
From BSSP Observations: "A wind slab triggered near the top of Cold Springs ran down and triggered a persistent slab around constriction level (see pics). This deeper failure occurred about 20cm off the ground at the Oct/Nov interface in a snowpack that was only about 1m deep." Photo BSSP
From BSSP Observations: "A wind slab triggered near the top of Cold Springs ran down and triggered a persistent slab around constriction level (see pics). This deeper failure occurred about 20cm off the ground at the Oct/Nov interface in a snowpack that was only about 1m deep." Photo BSSP
