Snowpack and Avalanche Discussion
<p>Last week it snowed 3-4 feet in the mountains south of Big Sky to West Yellowstone resulting in an avalanche warning and many avalanches. Since then the snowpack has gotten more stable and signs of instability are less frequent, but not absent. Yesterday, skiers in the southern Gallatin Range had rumbling collapses in a shallow snowpack and chose to avoid avalanche terrain (<strong><a href="https://www.mtavalanche.com/node/20144">details</a></strong>). On Sunday, skiers saw a large avalanche near Bacon Rind (<u><strong><a href="https://www.mtavalanche.com/node/20120">details</a></strong></u>), and in the two days prior Eric found a large avalanche in Taylor Fork (<u><strong><a href="https://www.mtavalanche.com/images/19/large-natural-avalanche-taylor-fo…;, <u><strong><a href="https://www.youtube.com/watch?v=kIPUqVPE0g8&list=PLXu5151nmAvRNl9ku…;). These slides broke on weak, sugary facets at the base of the snowpack. This layer still has potential to be triggered, especially on steep slopes that were wind-loaded over the weekend. Although snow loading has stopped, the recent signs of instability indicate avalanches are still possible. For today the avalanche danger is rated MODERATE on all slopes.</p>
<p>Over the weekend there was avalanche activity in the northern ranges and also around Cooke City. The avalanches were isolated and not widespread. The largest and scariest of them released on heavily wind-loaded slopes. These slopes are relatively easy to identify as their ridgelines are either scoured to the rocks or support large overhanging cornices. Some of these thick wind slabs overlay weak, faceted snow near the ground which is why they avalanche. A few recent examples:</p>
<ul>
<li>Around Cooke City Alex investigated a large slide on Henderson Mountain on Friday that was triggered by a cornice fall (<u><strong><a href="https://www.youtube.com/watch?v=oOjaEWyCVdI&index=2&list=PLXu51…;, <u><strong><a href="https://www.mtavalanche.com/node/20085">details</a></strong></u>). Yesterday, Ian and I checked out a small and deep hard slab avalanche under a scoured ridgeline on Crown Butte (<strong><a href="https://www.mtavalanche.com/images/19/avalanche-crown-butte-1">photo</a…;, <strong><a href="https://www.youtube.com/watch?v=GlOgKM58s-g&list=PLXu5151nmAvRNl9ku…;
<li>On Buck Ridge near Big Sky, Alex looked at two deep avalanches that were heavily wind-loaded and broke on faceted snow. The larger of the two was triggered from low on the slope (<strong><a href="https://www.mtavalanche.com/images/19/debris-slide-triggered-mcatee">ph…;, <strong><a href="https://www.youtube.com/watch?list=PLXu5151nmAvRNl9kuY3DxfWN1qiU7IeX9&a…;
</ul>
<p>The avalanche danger is decreasing but the consequences of being caught in a deep hard slab avalanche remains serious. Avoid steep, heavily wind-loaded slopes. Skiers will not be able to mitigate this problem with a ski-cut. Most slopes are strong and stable, but a few are not. Because we are human and prone to mistakes, sometimes we blow our slope assessment. Safe travel rituals are our safety net: traveling one at a time (literally) in avalanche terrain, carrying rescue gear and carefully assessing each slope. For today, the avalanche danger is rated MODERATE on wind-loaded slopes and LOW on all others.</p>
<p>If you get out and have any avalanche or snowpack observations to share, contact us via our <a href="https://www.mtavalanche.com/node/add/snow_observation">website</a>, email (<a href="mailto:mtavalanche@gmail.com">mtavalanche@gmail.com</a>), phone (406-587-6984), or Instagram (#gnfacobs).</p>
Upcoming Avalanche Education and Events
Our education calendar is full of awareness lectures and field courses. Check it out: Events and Education Calendar.
BOZEMAN
February 22 and 23, Women’s Companion Rescue Clinic, 6-8 p.m. Friday at REI, 10-4 Saturday in the field. More Info and Register.
