19-20

<p>On a spectrum of weak snow, the Lionhead area is the worst we have. Dave found half of the 3 foot deep snowpack consisting of loose, sugary snow (facets) that broke easily in stability tests (<u><strong><a href="https://youtu.be/VwdWKoEfnxE">video</a></strong></u&gt;). Further north around Bacon Rind and Taylor Fork it is not much better (<strong><a href="https://www.mtavalanche.com/node/21185">details</a></strong&gt;). &nbsp;Surrounding Big Sky the facet layer is not as thick, but it is showing signs of instability. The Yellowstone Club and Big Sky Ski Patrols are getting avalanches to break near the ground on these weak grains, which is relevant because their snowpack is similar to the backcountry.</p>

<p>Ian toured into Beehive Basin yesterday and found the snowpack to be stronger than expected. He saw no signs of instability, but was wary of extrapolating that to the entire northern Madison Range in light of the previous activity on Buck Ridge (<strong><a href="https://www.mtavalanche.com/images/19/natural-avalanches-buck-ridge">ph…;) and ski areas. Today’s snowfall and wind-loading will stress the snowpack and triggering a slide is likely. Avoiding avalanche terrain is a good strategy since the avalanche danger remains CONSIDERABLE.</p>

<p>The mountains around Cooke City have 4” of new snow and moderate southwest wind. Wind drifts will be thick and easy to trigger today. Avalanches will break at the new and old snow interface, and on a few slopes they may break deeper on a thin layer of facets that Ian and I found on Monday (<u><strong><a href="https://youtu.be/LGgBEFTzlN4">video</a></strong></u><strong&gt;, <u><a href="https://www.mtavalanche.com/images/19/scotch-bonnet-snowpack">photo</a>…;). With a snowtorm underway, the likelihood of triggering slides has increased. Visibility is poor so be extra careful about traveling underneath avalanche paths. For today, the avalanche danger is rated CONSIDERABLE on slopes with wind-drifted snow and MODERATE on all others.</p>

<p>Today’s new snow and wind will not help the stability in the Bridger Range. A foot under the snow surface is a layer of weak, faceted snow. Alex found a worrisome snow structure in his snowpit on Saddle Peak on Monday (<u><strong><a href="https://youtu.be/g4BPe7ydpEU">video</a></strong></u&gt;). Weak snow was underlying a hard, dense wind slab. Today’s new snow and windy weather will make it possible to trigger slides on fresh wind-drifts and on slopes with the faceted weak layer. For today, the avalanche danger is rated MODERATE.</p>

<p>In the northern Gallatin Range, skiers and ice climbers reported a lot of wind yesterday but not much snow moving. This will not be the case today. New snow last night and today will get blown into gullies and drifted at ridgelines. These fresh wind slabs will be possible to trigger. Cracks shooting out from your boots or skis is a sign to stay off the slope. For today, the avalanche danger is rated MODERATE on wind-loaded slopes and LOW on all others.</p>

<p>If you get out, please send us your observations no matter how brief. You can fill out an&nbsp;<u><strong><a href="https://www.mtavalanche.com/node/add/snow_observation">observation form</a></strong></u>, email us (<u><strong><a href="mailto:mtavalanche@gmail.com">mtavalanche@gmail.com</a></strong></u&gt;), leave a VM at 406-587-6984, or Instagram (#gnfacobs).</p>

<p>Weak, sugary snow near the ground plagues slopes from Lionhead to north of Big Sky. Yesterday, on a day <em>without</em> new snow, both the Yellowstone Club and Big Sky Ski Patrols got avalanches to break 2+ feet deep with explosives. Their snowpack is very similar to the backcountry and their ability to trigger avalanches is a window into the instability outside their boundaries. A skier in Bacon Rind in the southern Madison Range wrote, “…collapsing and whumpfing communicated across whole slopes, shook snow off trees, and sent birds flying.” Dave Zinn was teaching in Lionhead and had the thick layer of weak snow repeatedly break clean in his tests (<strong><a href="https://youtu.be/VwdWKoEfnxE">video</a></strong&gt;). Recent avalanches, collapsing and poor test scores are a trifecta of instability signs. Avoiding avalanche terrain is in your best interest since triggering avalanches is likely and the danger is rated <strong>CONSIDERABLE</strong>.</p>

<p>The snowpack in the Bridger Range is problematic. A layer of sugary, faceted snow a foot under the surface is weak. Without new snow and wind, the liklihood of triggering a slide is decreasing, but this layer is not getting stronger. Avalanches were triggered last week, skiers had a slope crack on Monday up Brackett Creek, and others had poor test scores (<u><strong><a href="https://www.mtavalanche.com/sites/default/files/styles/large/public/201…;) by Frazier Lake. On Monday, Alex skied onto Saddle Peak and got this layer to break clean underneath a hard slab of dense snow. His <u><strong><a href="https://youtu.be/g4BPe7ydpEU">video</a></strong></u&gt; illustrates the poor snow structure he found in his snowpit. Avalanches are still possible so be extra careful traveling in avalanche terrain. A slide involving a hard slab would be deadly. For today, the avalanche danger is rated <strong>MODERATE</strong>.</p>

<p>The mountains outside Cooke City had avalanches during and after Sunday’s 2 feet of new snow and strong wind (<strong><a href="https://www.mtavalanche.com/node/21147">avalanche activity details</a></strong>). Some avalanches broke just from the weight of the new snow while others avalanched on a thin layer of facets. Ian and I investigated this area on Monday and found this layer buried 1.5 feet deep and concluded it would not remain a problem for long (<u><strong><a href="https://youtu.be/LGgBEFTzlN4">video</a></strong></u><strong&gt;, <u><a href="https://www.mtavalanche.com/images/19/scotch-bonnet-snowpack">photo</a>…;). Yesterday skiers south of town dug a pit and found good, stable conditions on their tour. Even so, given the weekend’s new snow, wind-loading, and variable nature of this weak layer, it is still possible to trigger slides. Travel one at a time in avalanche terrain and back off at the first sign of instability (cracking, collapsing and recent avalanches no matter how small). For today, the danger is rated <strong>MODERATE</strong>.</p>

<p>The northern Gallatin Range is an island of stability in our forecast area. In Hyalite, climbers reported stable conditions as they ascended steep gullies of snow. This mirrors my assessment from the weekend. Weak, faceted snow can still be found on slopes where the snowpack is thin, but these areas are isolated and triggering avalanches is unlikely. For today, the avalanche danger is rated <strong>LOW</strong>.</p>

<p>If you get out, please send us your observations no matter how brief. You can fill out an&nbsp;<u><strong><a href="https://www.mtavalanche.com/node/add/snow_observation">observation form</a></strong></u>, email us (<u><strong><a href="mailto:mtavalanche@gmail.com">mtavalanche@gmail.com</a></strong></u&gt;), leave a VM at 406-587-6984, or Instagram (#gnfacobs).</p>

<p>The mountains from Big Sky to West Yellowstone have weak, sugary snow <em>near the ground</em> that is breaking. On Sunday, skiers in Lionhead near West Yellowstone had collapses and cracks shoot out from their feet (<u><strong><a href="https://www.mtavalanche.com/images/19/widespread-cracking-lionhead">pho…;) while snowmobilers on Buck Ridge saw natural avalanches (<u><strong><a href="https://www.mtavalanche.com/images/19/natural-avalanches-buck-ridge">ph…;, <u><strong><a href="https://www.mtavalanche.com/images/19/natural-avalanche-buck-ridge-2">p…;). Yesterday the Big Sky Ski Patrol triggered a large, 2 foot deep avalanche with explosives that broke on these facets. Sunday’s 8-10” of snow and wind-loading will continue to burden this unstable snowpack (<u><strong><a href="https://www.mtavalanche.com/images/19/ect-near-two-top">photo</a></stro…;, <u><strong><a href="https://www.youtube.com/watch?v=AbtyS3X7glA&amp;list=PLXu5151nmAvSbcbVf…;). Today, triggering avalanches on skis or a sled is likely. The snowpack is shallow, its structure is poor and is not expected to strengthen quickly. Watch your slope angles and stay clear of avalanche terrain as the danger is rated <strong>CONSIDERABLE</strong> on all slopes.</p>

<p>Outside Cooke City there is a thin layer of weak snow 1.5 feet under the surface. Sunday’s 14” (1.4” of <a href="https://www.nrcs.usda.gov/wps/portal/nrcs/detail/or/snow/?cid=nrcs142p2… water equivalent</a>) added enough stress to make slopes unstable. Snowmobilers triggered a slide on this layer near Lulu Pass and had to be rescued, while another sledder had a near-miss ascending Daisy Pass when a natural slide almost caught him (<a href="https://www.mtavalanche.com/node/21147"><u><strong>details</strong></u>…; <strong><a href="https://www.mtavalanche.com/images/19/natural-avalanche-crown-butte-0">…;). This heavy load also triggered natural slides on Scotch Bonnet (<strong><a href="https://www.mtavalanche.com/images/19/crown-scotch-bonnet">photo</a></s…;) and Miller Ridge. Ian and I went there yesterday and found deep snow, evidence of wind drifts from the strong winds, and a thin layer of facets breaking in our stability tests (<strong><a href="https://youtu.be/LGgBEFTzlN4">video</a&gt;, <a href="https://www.mtavalanche.com/images/19/scotch-bonnet-snowpack">photo</a>…;). Today, the avalanche danger is rated <strong>MODERATE</strong> because it is possible to trigger slides on this layer, although I do not expect it to remain a problem for the long term. &nbsp;</p>

<p>Alex went to Saddle Peak in the Bridger Range yesterday and was not pleased with his findings. Under a hard slab of wind blown snow he found a weak layer (facets) breaking in his stability tests (<strong><a href="https://youtu.be/g4BPe7ydpEU">video</a></strong&gt;). He and his partner skinned back to the ridge instead of skiing the slope. This was his 4^th visit to the range in 8 days and he remains concerned about this layer. Skiers on the Throne near Brackett Creek had cracking a foot deep on wind-loaded slopes, and another party found poor stability on this layer and stayed out of steep terrain (<u><strong><a href="https://www.mtavalanche.com/sites/default/files/styles/large/public/201…;). Get used to digging and testing this layer because it is going to be around for a while. It is still possible to trigger avalanches today and the danger is rated <strong>MODERATE</strong>.</p>

<p>The northern Gallatin Range is the most stable in our forecast area. The 4-6” of snow that fell on Sunday has bonded well to the old surface. Weak snow can be found, especially where the snowpack is thin, but without new snow or fresh wind drifts I do not expect avalanche activity. For today the avalanche danger is rated <strong>LOW</strong>.</p>