18-19

<p>Yesterday, Alex and his partner rode in the Lionhead area near West Yellowstone and observed numerous avalanches that occurred earlier in the week (<a href="https://www.mtavalanche.com/avalanche-activity">avalanche activity page</a>). Some failed naturally while others were human triggered. Avalanche activity has started to taper off, but a frighteningly weak snowpack structure continues to make human triggered avalanches possible (<strong><a href="https://www.mtavalanche.com/images/19/buried-weak-layers-cabin-creek">p…;).</p>

<p>Weak, sugary facets make up the foundation of most slopes in the southern ranges, in turn creating poor stability and tough riding conditions (<u><strong><a href="https://www.youtube.com/watch?v=BQ6V8-Pdb3M&amp;t=0s&amp;list=PLXu5151n…;). All steep slopes should be considered suspect and approached with caution. Terrain management is the best approach to safe riding today. Keep slope angles less than 35 degrees and avoid riding on low angle slopes connected to steeper slopes above.</p>

<p>Stability is gradually improving, but a weak snowpack structure makes human triggered avalanches possible and the avalanche danger is rated <strong>MODERATE</strong>. &nbsp;</p>

<p>Stability is improving but not perfect in the northern mountains and Cooke City area. Reports of cracking/collapsing and unstable test results continue to trickle in. Yesterday, skiers in Hyalite got unstable test results with an ECTP6 <strong>(<a href="https://www.mtavalanche.com/images/19/poor-structure-near-lick-creek">p…;), and also observed localized collapsing. Another group in the Northern Bridgers found a thin, weak snowpack on a north-facing slope which propagated in stability tests (<strong><a href="https://www.mtavalanche.com/images/19/weak-snow-northern-bridgers">phot…;). Although we haven’t received reports of avalanche activity in the last few days, these observations are a good reminder a poor snowpack structure exists on some slopes in the northern mountains.</p>

<p>The weakest snow can be found in areas where the snowpack is less than 3’ deep <u>(</u><u><strong><a href="https://www.youtube.com/watch?v=d2uyqO9S4Qw&amp;t=0s&amp;list=PLXu5151n…;, </strong></u><u><strong><a href="https://www.youtube.com/watch?v=cljvf0-9vyU&amp;list=PLXu5151nmAvRNl9ku…;. Before committing to avalanche terrain, put your shovel in the snow and do a quick stability test to assess the snowpack structure. &nbsp;</p>

<p>Today it may be possible to trigger avalanches in steep terrain on slopes with buried weak layers. For this reason the avalanche danger is rated <strong>MODERATE</strong>. &nbsp;</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>Despite the absence of new snow and wind, obvious signs of instability continue to take place in the southern Madison Range and mountains near West Yellowstone. Here is a short list of activity in the southern ranges.</p>

<ul>
<li>Cracking and collapsing, Taylor Fork southern Madison Range (<u><strong><a href="https://www.mtavalanche.com/images/19/cracking-and-collapsing-taylor-fo…;) 1/9</li>
<li>Natural avalanche, Lionhead area near West Yellowstone 1/9</li>
<li>Natural avalanches, Taylor Fork southern Madison Range (<u><strong><a href="https://www.mtavalanche.com/images/19/recent-slab-avalanche-taylor-fork…;) 1/9</li>
<li>Remotely triggered avalanches, Hellroaring Creek Centennial Range (<strong><a href="https://www.mtavalanche.com/images/19/remotely-triggered-slides2">photo…;) 1/8</li>
<li>Snowmobile triggered avalanche, Lionhead area near West Yellowstone 1/8</li>
<li>Cracking and collapsing, Specimen Creek southern Gallatin Range 1/8</li>
<li>View a more comprehensive list of activity <u><strong><a href="https://www.mtavalanche.com/avalanche-activity">here</a></strong></u>.<…;
</ul>

<p>The culprit of such an active snowpack is weak, faceted snow near the ground. This persistent weak layer is widespread and showing little sign of gaining strength (<u><strong><a href="https://www.youtube.com/watch?v=hugZzlbqGqg&amp;index=7&amp;t=0s&amp;li…;). Yesterday, Alex and his partner rode in Cabin Creek in the southern Madison Range a found a weak and unsupportable snowpack (<u><strong><a href="https://www.youtube.com/watch?v=BQ6V8-Pdb3M&amp;t=0s&amp;list=PLXu5151n…;). &nbsp;Slopes that received wind deposited snow earlier in the week will be most prone to producing avalanches, but non-wind loaded slopes also need to be approached with caution.</p>

<p>The simple strategy to staying safe is avoid all steep slopes. This also means avoiding low angle terrain attached to steeper slopes above. Warmer temperatures will gradually improve stability, but recent avalanche activity is a clear reminder the pack needs more time to gain strength. &nbsp;</p>

<p>Today, human triggered avalanches are likely on wind loaded slopes which have a <strong>CONSIDERABLE</strong> avalanche danger. Non-wind loaded slopes have a <strong>MODERATE</strong> avalanche danger.</p>

<p>Snowpack stability is better in the mountains around Bozeman, Big Sky and Cooke City, but a recent slide up Portal Creek in the northern Gallatin Range is a clear reminder these areas are not immune to avalanches (<u><strong><a href="https://www.mtavalanche.com/images/19/snowmobile-triggered-avalanche-po…;). Slopes that have wind drifted snow resting over weak facets near the ground are the most likely to produce unstable conditions. Yesterday, skiers near Naya Nuki in the northern Bridgers got unstable test results on a wind loaded slope with facets near the ground. The avalanche near Ross Peak last Saturday is a relevant example of this problem (<u><strong><a href="https://www.mtavalanche.com/node/19583">details</a></strong></u><u&gt;)</u>.&nbsp;Not all wind loaded slopes have a poor snowpack structure, so it’s important to assess each slope carefully.</p>

<p>Non-wind loaded slopes are more stable, but still hold the potential to produce slides. On slopes where the snowpack is shallow (less than 3’ deep), you’ll likely find a weak, faceted snowpack (<strong><a href="https://www.youtube.com/watch?v=d2uyqO9S4Qw&amp;t=0s&amp;list=PLXu5151n…;, <a href="https://www.youtube.com/watch?v=cljvf0-9vyU&amp;list=PLXu5151nmAvRNl9ku…;). The best way to determine if these slopes are unstable is watch for signs of instability such as cracking/collapsing or dig and do a stability test. If you experience whumphing and cracking or get unstable test results, steer clear of avalanche terrain.</p>

<p>An additional problem today will be loose wet avalanches on steep, sun exposed slopes. Watch for roller balls or small point releases and move to shadier aspects if these signs are present.</p>

<p>Stability is improving, but human triggered avalanches remain possible and the avalanche danger is rated <strong>MODERATE</strong>.&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;</p>