17-18

<p>The mountains near Cooke City received 6 feet of snow equal to 6.2” of snow water equivalent (SWE) over the last week. This steady, heavy load combined with strong winds made large natural and human triggered avalanches likely the last couple days (<a href="https://www.youtube.com/watch?v=6WwB3XBH5k8&amp;list=PLXu5151nmAvQSYtIf…;). Yesterday, skiers near Cooke City saw multiple recent avalanche crowns and saw one avalanche occur (<strong><a href="https://www.mtavalanche.com/images/18/natural-avalanche-mt-abiathar">ph…;). With minimal new snow and wind since yesterday, natural avalanches are not likely. The snowpack will adjust to the recent load relatively quick, but deserves a day or two to do so. Today, large wind slabs are easy to trigger and wind loaded slopes should be avoided. Be cautious of large cornices along ridgelines and pillows of snow below (<strong><a href="https://www.mtavalanche.com/images/18/examples-wind-loaded-terrain">pho…;). On non-wind loaded slopes, loose sluffs and slab avalanches of recent snow are possible. Avoid steep slopes if you see collapsing or cracks shooting across the snow surface. Avalanche danger today is <strong>CONSIDERABLE</strong> on all slopes.</p>

<p>The southern Madison and Gallatin ranges and mountains near West Yellowstone received a couple inches of snow each day of over the past week. Strong westerly winds drifted recent snow into slabs that are possible to trigger near ridgelines, below cornices, and on cross-loaded terrain features. Avoid fresh drifts and pillows of snow on steep slopes.</p>

<p>A second concern is a layer of weak surface hoar buried 1-2’ deep. Eric found this unstable layer in Taylor Fork on Wednesday (<a href="https://youtu.be/2mj4jkCkEpc"><strong>video</strong></a><strong>,</stro…; <a href="https://www.mtavalanche.com/images/18/buried-surface-hoar-taylor-fork">…;), and Doug and I found it near Hebgen Lake last Sunday (<a href="https://www.youtube.com/watch?v=CFzhlPk5DZw&amp;list=PLXu5151nmAvQSYtIf…;). This layer is not widespread, but can break under the weight of a skier or rider. Snowmobilers in the southern Madison Range saw an avalanche yesterday that probably broke on this layer (<strong><a href="https://www.mtavalanche.com/images/18/avalanche-near-tepee-basin">photo…;), which is a clear sign of instability. Carefully assess the snowpack and practice cautious route finding if riding steep terrain. Today, avalanches are possible and avalanche danger is <strong>MODERATE</strong> on all slopes.</p>

<p>In the mountains near Bozeman and Big Sky wind loaded slopes and large cornices deserve extra caution. Eric went to the Throne in the northern Bridger Range yesterday and found a deep and generally stable snowpack on non-wind loaded slopes (<strong><a href="https://youtu.be/GOpY8hRn4iM">video</a></strong&gt;). Yesterday morning, a skier north of Bridger Bowl unintentionally triggered a large cornice that entrained recent snow and ran into flat terrain across a common skin track (<strong><a href="https://www.mtavalanche.com/images/18/cornice-triggered-hourglass-chute…;, <strong><a href="https://www.mtavalanche.com/images/18/debris-cornice-triggered-slide-ho…;, <strong><a href="https://www.mtavalanche.com/images/18/cornice-chunk-and-debris-below-ho…;). Minimal wind today makes fresh wind slabs unlikely. However, recent activity is a sign to avoid wind loaded slopes near ridgelines and below large cornices, and to stay far from the leeward edge when travelling along ridgelines (<strong><a href="https://www.mtavalanche.com/images/18/small-natural-avalanches-hyalite"…;). Avalanche danger today is <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>