22-23

<p>The mountains around West Yellowstone and Cooke City received 4-6” of new snow, and the wind is averaging 25-30 mph from the southwest. During the day, the mountain will receive an additional 6-8” of snow.</p>

<p>During the last significant pulse of snow at the end of last week, avalanches broke naturally up to 1000’ wide and 4-6’ deep on many slopes at Lionhead Ridge (<a href="https://www.mtavalanche.com/node/28611"><strong><span>photos and details</span></strong></a>). In Cooke City, natural and human-triggered avalanches were large and plentiful. Alex made a <a href="https://www.youtube.com/watch?v=RTMemSftJqs"><strong><span>video</span>…; describing some of these slides. Others submitted <a href="https://www.mtavalanche.com/snow-observations-list"><span>observations<…; describing snapping trees and powder clouds coming from a human-triggered avalanche on Scotch Bonnet (<a href="https://www.mtavalanche.com/node/28620"><strong><span>observation and photo</span></strong></a>) and a 2000’ wide and 4-6’ deep avalanche near Abundance Lake (<a href="https://www.mtavalanche.com/node/28614"><strong><span>photos and details</span></strong></a>).</p>

<p>Snow will continue throughout the day, and we expect to get reports of more large avalanches. Avoid high-elevation terrain that is likely wind-loaded and the runout zones below where natural and human-triggered avalanches are likely. The avalanche danger is HIGH on wind-loaded slopes and CONSIDERABLE on all others.</p>

<p>The Southern Gallatin and Southern Madison Ranges received 3-4” of new snow and the wind is gusting to 40 mph from the southwest. Snow will continue, with 4-8” possible by this evening. Avoid wind-loaded slopes where human-triggered avalanches are likely. This includes most high-elevation slopes exposed to significant wind, areas below cornices, and slopes where you feel the snow surface stiffen or crack. Avalanches will most likely consist of the recent snow, breaking 1-2’ deep. However, a recent history of large natural avalanches, including one on Red Mountain that broke up to 15’ deep (<a href="https://www.mtavalanche.com/node/28633"><strong><span>photos and observation</span></strong></a>), one over 1000’ wide on Electric Peak (<a href="https://www.mtavalanche.com/node/28602"><strong><span>photos and observation</span></strong></a>) and two monsters in Tepee Basin (<a href="https://www.mtavalanche.com/node/28603"><strong><span>photos and observation</span></strong></a>), show the potential for large avalanches breaking multiple feet deep and over 1000’ wide.</p>

<p>Seek out terrain sheltered from the wind where a good snowpack assessment and safe travel protocols are strongly advisable or stay on slopes less than 30 degrees steep. The danger is CONSIDERABLE on wind-loaded slopes and MODERATE on all others.</p>

<p>A trace to 3” of snow fell in the mountains around Bozeman and Big Sky, with a few more expected today. Strong winds gusting to 70 mph in Big Sky and Hyalite Canyon are blowing snow at all elevations. Yesterday in Beehive Basin, I outlined our concerns about wind-loaded slopes and deep slab avalanches (<a href="https://www.youtube.com/watch?v=nSi90vR6ayI"><strong><span>video</span>…;

<p>When deep slab avalanches like the one I investigated on <a href="https://youtu.be/42Zk3eLEMvE"><strong><span>Hyalite Peak</span></strong></a> last week and one in the Bridger Range this weekend (<a href="https://www.mtavalanche.com/node/28631"><strong><span>photos and observation</span></strong></a>) are on the table, follow a conservative travel plan. Choose sheltered terrain on slopes with fewer complicating factors like rock, cliffs and walls of trees that increase the consequences of a mistake. Evaluate the snowpack for instability and follow safe travel protocols. The avalanche danger is rated MODERATE.</p>

<p><span>Please share avalanche, snowpack or weather observations via our<a href="https://www.mtavalanche.com/node/add/snow_obs"><span&gt; </span></a><a href="https://www.mtavalanche.com/node/add/snow_obs"><strong><span>website</s…;, email (<strong>mtavalanche@gmail.com</strong>), phone (406-587-6984), or Instagram (#gnfacobs). </span></p>

<p>The Gallatin National Forest Avalanche Center is issuing a backcountry avalanche warning for the Centennial Mountains. Very dangerous avalanche conditions exist. Human-triggered and natural avalanches are likely on all steep slopes. The mountains received 14” of new snow, and the wind is blowing 30-45 mph from the southwest. During the day, Island Park could see an additional 12” of snow.</p>

<p><span><span><span><span><span><span>Backcountry travelers should stay off steep slopes and away from the bottom of steep slopes.&nbsp;</span></span></span></span></span></span>Avalanches can be triggered from flat terrain. Steep slopes can avalanche far above and run into lower-angled terrain. Traveling in and below steep is not recommended.&nbsp;</p>