17-18

<p>The Lionhead area near West Yellowstone has all the red flags of an unstable, dangerous snowpack. The list starts with 2 feet of snow equal to 2” of <a href="https://www.nrcs.usda.gov/wps/portal/nrcs/detail/or/snow/?cid=nrcs142p2… water equivalent</a> (SWE) on Friday, strong wind last night, and weak facets buried 3-4’ deep. Additionally, there have been snowmobile triggered avalanches or large collapses almost daily for two weeks (<a href="https://www.mtavalanche.com/images/18/remote-trigger-lionhead"><strong>…;, <strong><a href="https://www.mtavalanche.com/images/18/snowmobile-triggered-avalanche-li…;), and three people killed in avalanches nearby in the last three weeks. I was on Lionhead Ridge yesterday and my group collapsed a large, low angle slope after finding stable results in our stability tests (<strong><a href="https://youtu.be/y8O0iWplhS0">video</a></strong&gt;). Signs of instability are slowly becoming less obvious. It may not be the first person on a slope to trigger it, but large, deadly avalanches are likely today. Avoid steep slopes and terrain below. Avalanche danger is <strong>HIGH</strong> on wind loaded slopes and <strong>CONSIDERABLE</strong> on all other slopes.</p>

<p>In the Bridgers, Gallatin and Madison Ranges, and mountains near Cooke City 1-1.5 feet of snow (1-1.5” SWE) that fell Friday makes avalanches possible today. Strong wind in some locations drifted this snow into fresh slabs that were easily triggered by skiers in the Bridger Range (<strong><a href="https://www.mtavalanche.com/images/18/fairy-lake-wind-slab">photo</a></…;) and riders in Taylor Fork (<strong><a href="https://www.mtavalanche.com/images/18/small-avalanche-wind-loaded-slope…;) yesterday. Today, wind slabs 1-3 feet thick near ridgelines or the edges of cliffs and gullies are easy to trigger.</p>

<p>Recent snow also buried a weak layer of surface hoar (<strong><a href="https://www.mtavalanche.com/images/18/buried-surface-hoar-lionhead">pho…;). The distribution of this weak layer is uncertain, but is more likely on slopes sheltered from sun and wind. Avalanches are possible where this weak layer was buried, and careful snowpack assessment is essential before travel in avalanche terrain. Quickly dig 1-2’ to rule out this&nbsp;weak layer&nbsp;before riding any steep slope.</p>

<p>Avalanches breaking on facets 2-4’ deep are becoming less likely, but are possible and could be large (<strong><a href="https://youtu.be/Z5zkCJfIfdI">video</a></strong&gt;). This weak layer is most unstable and likely to trigger where the snowpack is 3-5’ deep or shallower. Skiers near Cooke City earlier this week saw avalanches and had large collapses on this layer (<a href="https://www.mtavalanche.com/images/18/unstable-snow-avalanche-and-colla…;). Be cautious of steep slopes where the snowpack is relatively shallow or highly variable.</p>

<p>Today, avalanche danger is <strong>CONSIDERABLE</strong> on wind loaded slopes and <strong>MODERATE</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>