Snowpack and Avalanche Discussion
<p>Yesterday, an avalanche buried a snowmobiler whose head was five feet under the snow and only his foot sticking out. Partners successfully resuscitated the rider, and we are happy to report that everyone was okay in the end (<a href="https://www.mtavalanche.com/node/34395"><span>more information</span></a>). We don’t know all the details, but we know that avalanche conditions are dangerous in the mountains around Cooke City.</p>
<p>Human-triggered <strong>wind slab avalanches</strong> breaking 1-2 feet deep on freshly drifted slopes are likely. Yesterday, a large natural or rider-triggered avalanche failed over 100 feet wide on the north face of Crown Butte (<a href="https://www.mtavalanche.com/node/34397"><span>info and photos</span></a>). This weekend, skiers and riders reported many human-triggered and natural avalanches north of Cooke City breaking on slopes where strong wind deposited drifting snow (<a href="https://www.mtavalanche.com/node/34368"><span>observation and photos</span></a>, <a href="https://www.mtavalanche.com/node/34360"><span>photos and details</span></a>). Avoid wind-loaded slopes and find softer snow and safer conditions in wind-sheltered terrain.</p>
<p>This weekend, Alex and a second group of riders triggered slopes that broke 150-250 feet wide and two feet deep from low-angle terrain nearby (<a href="https://www.youtube.com/watch?v=pniI5ENMxMU"><span>video</span></a>, <a href="https://www.mtavalanche.com/node/34344"><span>observation</span></a>). Reduce your exposure to steep slopes when these <strong>persistent slab avalanches</strong> breaking on buried weak layers are in the mix. Extensive snowpack analysis is required for a safer day in and around avalanche terrain or choose to play in terrain less than 30 degrees steep.</p>
<p><span>Cautious route-finding is essential, and the danger is CONSIDERABLE. </span></p>
<p>In the Southern Gallatin and Southern Madison Ranges and mountains near West Yellowstone, human-triggered <strong>persistent slab avalanches</strong> breaking 1-3 feet deep on buried weak layers are possible. Avoiding steep faces at upper elevations is insufficient because we have seen (and triggered) slides at lower elevations. Mark and I looked at a pair of snowmobiler-triggered avalanches in Tepee Basin that broke 2 feet deep and over 100 feet wide on treed mid-elevation slopes last weekend (<a href="https://www.mtavalanche.com/node/34301"><span>details and photos</span></a>, <a href="https://www.mtavalanche.com/node/34341"><span>details and photos 2</span></a>, <a href="https://youtu.be/jdtQgYx3MNA?feature=shared"><span>video</span></a>). A week ago, we triggered a similar slide in Lionhead (<a href="https://www.mtavalanche.com/node/34268"><span>video</span></a>), an avalanche in Black Canyon piled debris 15 feet deep (<a href="https://www.mtavalanche.com/node/34266"><span>details</span></a>), and Alex and Haylee heard a loud <em>whumph</em> in the Taylor Fork when a slope collapsed (<a href="https://www.youtube.com/watch?v=uXj3ZtkUM5s"><span>video</span></a>). Assess for instability associated with persistent weak layers or play in terrain less than 30 degrees steep.</p>
<p><strong>Wind slab avalanches</strong> breaking less than a foot deep are possible on steep wind-loaded slopes. Avoid steep slopes with recent drifts where slides could carry you into terrain traps like trees, cliffs and gullies.</p>
<p><span>The avalanche danger is MODERATE. </span></p>
<p>Strong winds drifted several inches of recent snow in the mountains around Bozeman, Big Sky and Island Park, making <strong>wind slab avalanches </strong>up to a foot deep the primary concern. On Monday, a rider escaped a small wind slab avalanche on Cedar Mountain (<a href="https://www.mtavalanche.com/node/34357"><span>details and photos</span></a>). Yesterday in the Bridger Range, we were blasted by blowing snow and saw cracking in drifts (<a href="https://youtube.com/shorts/AWBO2tGdnRM?feature=share"><span>video</span…;). These avalanches are most dangerous on slopes with terrain traps, including cliffs, rocks, trees and gullies. Maintain increased levels of suspicion for instability on slopes below cornices and areas with shooting cracks, recent avalanche activity or a stiffening of the snow surface. If you avoid recently wind-loaded slopes, you will find generally safe conditions.</p>
<p><span>The danger is MODERATE on wind-loaded slopes and LOW on all others. </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
