20-21

<p>The mountains have not received new snow the last three days, and westerly wind has been light to moderate. A few days without snow and heavy wind-loading lowers the avalanche danger and likelihood of triggering an avalanche, but conditions are far from safe. It is still possible to trigger big avalanches. Yesterday skiers reported many large collapses in low angle terrain in the southern Madison Range (<strong><a href="https://www.mtavalanche.com/node/23723">details</a&gt;, <a href="https://www.mtavalanche.com/node/23726">details and photo</a></strong>), and a couple in Hyalite (<strong><a href="https://www.mtavalanche.com/node/23727">details</a></strong&gt;). These are signs that on steep slopes it is possible to trigger a large avalanche breaking on weak, sugary snow buried 1-3 feet deep.</p>

<p>Natural and human triggered avalanches over the last week show us the nature of slides that we can trigger today (<strong><a href="https://www.mtavalanche.com/weather/wx-avalanche-log">weather and avalanche log</a></strong>). These photos (<strong><a href="https://www.mtavalanche.com/images/21/snowmobiler-triggered-slide-lionh…;, <strong><a href="https://www.mtavalanche.com/images/21/snowmobile-triggered-avalanche-li…;) of avalanches triggered at Lionhead Ridge on Saturday are good examples. Many recent avalanches were triggered from low angle terrain connected to steep slopes (<strong><a href="https://www.mtavalanche.com/node/23650">Cinnamon Creek avy photo</a></strong>, <strong><a href="https://www.mtavalanche.com/images/21/skier-remotely-triggered-avalanch…. Madison avy photo</a></strong>). Some slides propagated wide across terrain features and multiple starting zones (<strong><a href="https://www.mtavalanche.com/node/23678">Flanders avy photos and video</a></strong>, <strong><a href="https://www.youtube.com/watch?v=VCI4BiZ14CY">Buck Ridge avy video</a>, <a href="https://www.mtavalanche.com/images/21/large-shooting-cracks-bridgers">w… cracks in Bridgers photo</a></strong>). Today, large to very large avalanches are possible to trigger and the avalanche danger is MODERATE. Careful snowpack assessment and cautious route selection are essential to travel on, underneath or adjacent to steep slopes.</p>

<p>In the mountains near Cooke City some slopes have a weak layer of sugary facets buried 1.5-2’ deep. On Friday and Saturday there were multiple human triggered avalanches that broke on this layer, including one on Friday that caught and partially buried three skiers and caused one of them to be evacuated by helicopter due to serious injuries (<a href="https://www.mtavalanche.com/node/23644"><strong>photos and details</strong></a>). Doug and Dave visited the site on Saturday and made a <strong><a href="https://www.youtube.com/watch?v=0x5E-7XHwG8&amp;list=PLXu5151nmAvQDzKmH… describing the slide</a></strong>, and we compiled this <strong><a href="https://www.mtavalanche.com/sites/default/files/accident-reports/2021-0… report</a></strong>. Other recent slides north and west of Cooke City (<strong><a href="https://www.mtavalanche.com/images/21/skier-triggered-near-meridian-2">…;, <strong><a href="https://www.mtavalanche.com/images/21/skier-triggered-slide-north-cooke…;) show us this weak layer of facets is not completely isolated and needs to be kept in mind. Diligently search for this weak layer by digging and performing stability tests. Be cautious of slopes with a relatively shallower snowpack, and wind loaded slopes where weak snow may be buried under a thicker slab. Today, avalanches are possible and avalanche danger is rated MODERATE.</p>

<p>If you get out, please send us your observations no matter how brief. You can submit them via our <a href="https://www.mtavalanche.com/node/add/snow_observation"><strong>website<…;, email (<a href="mailto:mtavalanche@gmail.com"><strong>mtavalanche@gmail.com</strong></a…;), phone (406-587-6984), or Instagram (#gnfacobs).</p>