18-19

<p>In the mountains south of Big Sky to West Yellowstone a foot of new snow (.6-1” of <a href="https://www.nrcs.usda.gov/wps/portal/nrcs/detail/or/snow/?cid=nrcs142p2… water equivalent</a>) and strong wind will cause natural avalanches on wind loaded slopes, and avalanches will be easy to trigger on all steep slopes. The snowpack is poorly supported by 1.5’ of weak, sugary facets on the ground (<u><strong><a href="https://www.mtavalanche.com/images/19/poor-structure-s-madison-range">p…;), which makes it possible for avalanches to break far and wide. Doug rode into Lionhead Ridge yesterday and found this poor snowpack structure and unstable new snow (<strong><a href="https://www.youtube.com/watch?v=hugZzlbqGqg&amp;t=0s&amp;list=PLXu5151n…;). Eric and I found a similar, slightly weaker snowpack in the southern Madison Range last week (<u><strong><a href="https://www.youtube.com/watch?v=fXzzClQFS5s&amp;t=0s&amp;list=PLXu5151n…;, <u><strong><a href="https://www.youtube.com/watch?v=l0aklSLqYaM&amp;list=PLXu5151nmAvRNl9ku…;, <u><strong><a href="https://www.youtube.com/watch?v=zj26vpS2WE0">video</a></strong></u&gt;). Doug’s video from yesterday shows the weak snow at the ground is getting more stubborn in stability tests, but the real test will be the stress of new snow and fresh wind drifts today.</p>

<p>Avoid riding on steep slopes and through avalanche runout zones today. Avalanche danger is HIGH on wind loaded slopes and CONSIDERABLE on all other slopes.</p>

<p>Since yesterday the mountains near Cooke City got 9” of new snow equal to .6” of <a href="https://www.nrcs.usda.gov/wps/portal/nrcs/detail/or/snow/?cid=nrcs142p2… water equivalent</a> (SWE). Today, more snow is expected and strong wind will continue out of various directions (southwest to northwest). On wind loaded slopes, natural avalanches are possible and fresh drifts of snow will be easy to trigger and can break deeper and wider on buried weak layers (<u><strong><a href="https://www.youtube.com/watch?v=W6iS9ManzPo&amp;t=0s&amp;list=PLXu5151n…;). On non-wind loaded slopes, loose snow and slab avalanches in the storm snow are likely. These avalanches can also break far and wide where new snow fell on a weak snowpack, such as what Doug found last week south of Cooke (<u><strong><a href="https://www.youtube.com/watch?v=4Vb2Y4UZJ1Q&amp;t=0s&amp;list=PLXu5151n…;). Today, avalanches are easy to trigger and avalanche danger is <strong>CONSIDERABLE</strong>. Danger could rise to <strong>HIGH</strong> on wind loaded slopes if heavy snowfall continues today.</p>

<p>In the mountains near Bozeman and Big Sky, weak, sugary snow that formed in December is buried 1-2’ deep and creates a poor snowpack structure. We received reports of large collapses most days the past week (<u><strong><a href="https://www.mtavalanche.com/weather/wx-avalanche-log">Activity log</a></strong></u>, <u><strong><a href="https://www.mtavalanche.com/images/19/collapse-and-crack-road-cut">phot…;). On Saturday, in Middle Basin a skier triggered an avalanche that broke on hollow, sugary snow 1-2’ deep (<u><strong><a href="https://www.mtavalanche.com/images/19/skier-triggered-avalanche-middle-…;, <u><strong><a href="https://www.mtavalanche.com/node/19567">details</a></strong></u&gt;) and riders in the northern Bridgers saw a large avalanche (<strong><a href="https://www.mtavalanche.com/images/19/avalanche-near-throne">photo</a><…;). A few inches of new snow today and strong wind will form fresh drifts that are easy to trigger and could break deeper on weak, sugary snow. Avalanche danger is <strong>MODERATE.</strong> Danger could rise to <strong>CONSIDERABLE</strong> on wind loaded slopes with more than a couple inches of new snow today.</p>

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

<p>We are issuing an avalanche warning for the Centennial Range due to strong wind and heavy snowfall (1.3+" of SWE)&nbsp;loading&nbsp;a weak snowpack. See the Centennial's&nbsp;<a href="https://www.mtavalanche.com/forecast/centennials">regional page</a> for more info.</p>