17-18

<p>Strong winds out of the west-southwest continue to hammer the Bridger Range. These relentless winds have affected the snowpack on all aspects and elevations. Some slopes are scoured to the Thanksgiving ice crust, while others are heavily loaded. Yesterday, the Bridger Bowl Ski Patrol did control work in anticipation of today’s opening and triggered&nbsp;wind slabs across the mountain. These slabs are becoming more stubborn but could still fail under the weight of a skier or rider.</p>

<p>Wind loaded slopes are also the main avalanche concern in the mountains around Cooke City. This problem is more confined to upper elevation ridgelines. Yesterday and overnight, winds around Cooke City blew 30-50 mph out of the W-NW. These strong winds likely formed fresh wind slabs in upper elevation, leeward terrain. Exercise caution when traveling in wind loaded areas, especially in steeper-high consequence terrain.</p>

<p>Outside of the wind loaded slopes, the snowpack is mostly stable in the Bridger Range and mountains around Cooke City (<a href="https://youtu.be/yqJ9-AsTwOQ"><strong>video</strong></a&gt;).</p>

<p>Today, human triggered avalanches are possible on wind loaded slopes which have a <strong>MODERATE</strong> avalanche danger. Non-wind loaded slopes have a <strong>LOW</strong> avalanche danger.</p>

<p>Clear and calm conditions yesterday gave wind slabs that formed earlier in the week a chance to stabilize. Yesterday, we travelled into wind loaded gullies around Hyalite to assess stability for the Bozeman Ice Festival. We found mostly stable conditions, with recently formed wind slabs bonding well to the old snow surface (<strong><a href="https://www.youtube.com/watch?v=RqIx4CG5zrM">video</a></strong&gt;). This is consistent with observations from around the area (<strong><a href="https://www.youtube.com/watch?v=pOSSQJpkbRo&amp;index=2&amp;list=PLXu51…;

<p>Yesterday, the Yellowstone Club Ski Patrol did extensive control work for the first time this season with minimal results. At this point, the snowpack in the Yellowstone Club is representative to a backcountry snowpack. This a solid indicator stability is generally good. This is consistent with what Alax and his partner found in the Taylor Fork yesterday.</p>

<p>Without a significant weather change, the snowpack will remain generally stable. While natural and human triggered avalanches are unlikely, they are not impossible. Use standard backcountry protocol and always be thinking about the consequence of a slide.</p>

<p>Today, generally safe avalanche conditions exist and the avalanche danger is rated <strong>LOW</strong>.</p>

<p>If you get out and have any avalanche or snowpack observations to share, drop a line via our <a href="https://www.mtavalanche.com/node/add/snow_observation">website</a&gt;, email (<a href="mailto:mtavalanche@gmail.com">mtavalanche@gmail.com</a&gt;), phone (406-587-6984), or Instagram (#gnfacobs).</p>

<p><a>Wind slabs in the Bridger Range remain a problem on all aspects and elevations.</a> Yesterday, the Bridger Bowl Ski Patrol triggered numerous slides during control work, all of which occurred on wind loaded slopes. The most significant slide broke 4’ deep and 100’ wide near the south boundary of the ski resort. Other slides breaking 12- 20” deep occurred across the mountain. <a>These slides are bull’s eye information the snowpack has not yet adjusted to the heavy snow and wind from the past few days.</a> Slides have been running on the Thanksgiving ice crust and have not broken into deeper layers. In general, the old snow underneath this crust is strong and stable (<a href="https://youtu.be/yqJ9-AsTwOQ"><strong>video</strong></a&gt;).</p>

<p>Today, wind loaded slopes will remain sensitive to human triggers. For this reason, the avalanche danger is rated <strong>CONSIDERABLE</strong> on all wind-loaded slopes and <strong>MODERATE</strong> on all others.</p>

<p>The mountains around Big Sky, West Yellowstone and Cooke City including Hyalite have been mostly spared from the strong winds that nuked the Bridgers over the past few days. As a result, wind loading has been light with the exception of some transport occurring along the ridgelines (<a href="https://www.mtavalanche.com/images/17/buck-ridge-cornices"><strong>phot…;). Today, upper elevation slopes leeward to west-northwest winds could harbor the occasional wind slab. I don’t expect these to be overly sensitive to human triggers, but it’s worth assessing wind loaded slopes carefully before committing to serious terrain. If wind drifts present signs of instability such as shooting cracks or collapsing, it will be best to avoid these areas and seek terrain that is less wind loaded.</p>

<p>Aside from wind loaded slopes, the snowpack is mostly stable. Yesterday, I rode in Tepee Basin in the southern Madison Range and found stable snow in multiple snowpits. This is consistent with what Doug found on Buck Ridge on Tuesday (<a href="https://www.mtavalanche.com/snowpits"><strong>snowpits</strong></a&gt;, <a href="https://youtu.be/pOSSQJpkbRo"><strong>video of Buck Ridge</strong></a>). It’s also similar to what skiers and riders are finding around Cook City.</p>

<p>For today, the avalanche danger is rated <strong>MODERATE</strong> on wind-loaded slopes and <strong>LOW</strong> on all other slopes.</p>

<p>If you get out and have any avalanche or snowpack observations to share, drop a line via our <a href="https://www.mtavalanche.com/node/add/snow_observation">website</a&gt;, email (<a href="mailto:mtavalanche@gmail.com">mtavalanche@gmail.com</a&gt;), phone (406-587-6984), or Instagram (#gnfacobs).</p>

<p>The story in the Bridger Range is simple: yesterday’s strong wind blew Sunday and Monday’s 16” of new snow into wind slabs that avalanched on many slopes. The winds were unusual and did not come from any one direction. They swirled around and mostly hit mid to lower elevation terrain. The Bridger Bowl Ski Patrol was able to avalanche wind slabs with ski cuts all over the mountain, not just the ridgeline. The slabs were sliding on the Thanksgiving ice crust and did not break into deeper layers. In general, the old snow underneath this crust is strong and stable (<a href="https://youtu.be/yqJ9-AsTwOQ"><strong>video</strong></a&gt;).</p>

<p>Avoid slopes where wind drifted snow has formed slabs. Shooting cracks and recent avalanches are warning signs of instability. For today the avalanche danger is rated CONSIDERABLE on all wind-loaded slopes and MODERATE on all others.</p>

<p>In the mountains around Hyalite, Big Sky and Cooke City, westerly wind blew at the ridgelines with many upper elevation slopes stripped bare as others grew cornices (<a href="https://www.mtavalanche.com/images/17/buck-ridge-cornices"><strong>phot…;). A skier up Hyalite noted that several cornices broke at ridgelines but did not trigger avalanches. Though slopes are generally stable (<strong><a href="https://www.mtavalanche.com/snowpits">snowpits</a></strong&gt;, <strong><a href="https://youtu.be/pOSSQJpkbRo">video of Buck Ridge</a></strong>) it is possible to trigger small wind slabs near ridges or in gullies. For today, the avalanche danger is rated MODERATE on all wind-loaded terrain and LOW on all other slopes.</p>

<p>The southern Madison Range, southern Gallatin Range, and mountains around West Yellowstone have a stable snowpack that could handle the new snow from Sunday (6”). Winds blew at the ridgelines after the storm but these slabs bonded to the old snow surface and are unlikely to move. For today the avalanche danger is rated LOW since they have generally safe avalanche conditions.</p>

<p>If you get out and have any avalanche or snowpack observations to share, drop a line via our <a href="https://www.mtavalanche.com/node/add/snow_observation">website</a&gt;, email (<a href="mailto:mtavalanche@gmail.com">mtavalanche@gmail.com</a&gt;), phone (406-587-6984), or Instagram (#gnfacobs).</p>