20-21

<p>The snowpack throughout our advisory area is a mixed bag of conditions: powdery or windblown up high, mashed potatoes down low. The chances of triggering an avalanche is decreasing without a load of new snow or active wind-loading, but it still remains possible. There was natural avalanche activity on wind-loaded slopes Sunday and Monday. Winds hit 100 mph Sunday night and felled trees which Ian and Dave had to lumberjack through to get into Taylor Fork yesterday. They found recent avalanches in Sunlight Basin (<a href="https://www.mtavalanche.com/images/21/natural-avalanche-sunlight-basin"…;) and Sage (<a href="https://www.mtavalanche.com/images/21/natural-avalanche-sage-basin-0"><…;), and caution us that we can still trigger wind slabs (<a href="https://youtu.be/kbS857qFfw8"><strong><u>video</u></strong></a&gt;).&nbsp;</p>

<p>Deeper in the snowpack are sugary facets (depth hoar) near the ground. Over the weekend a skier triggered an 8-10’ deep avalanche on this layer on Mt Blackmore (<a href="https://www.mtavalanche.com/node/24732"><strong><u>photos and details</u></strong></a>), and another deep slide was seen in Flanders Creek (<a href="https://www.mtavalanche.com/images/21/natural-deep-slab-near-flanders">…;) and MacAtee Basin (<a href="https://www.mtavalanche.com/node/24748"><strong><u>photo and details</u></strong></a>). This layer has been a non-stop worry since November and these slides illustrate that being worried is still warranted.&nbsp;</p>

<p>The sun will be strong today, but wind and cool temperatures will temper wet avalanches from getting big. On sunny slopes expect small, loose, wet slides in the top few inches of the snowpack.</p>

<p>Being outside on a beautiful day will feel wonderful, but has no bearing on snowpack stability. Wind-loaded slopes can still be triggered. Before you commit to avalanche terrain dig down a couple feet and confirm there is not an unstable layer underfoot. Overall, triggering slides remains possible and if you are extra unlucky, they could break deep. Today the avalanche danger is rated MODERATE on all slopes.&nbsp;</p>

<p>If you get out, please send us your observations no matter how brief. You can submit them via our <a href="https://www.mtavalanche.com/node/add/snow_observation"><strong><u>websi…;, email (<a href="mailto:mtavalanche@gmail.com"><strong><u>mtavalanche@gmail.com</u></str…;), phone (406-587-6984), or Instagram (#gnfacobs).</p>

<p>There are three distinct avalanche concerns across the advisory area today.</p>

<ol start="1" type="1">
<li><strong>Fresh Drifts of snow and wind-loaded slopes:</strong> For the last two days southwest to northwest winds blasted the mountains with gusts regularly reaching 70-85 mph with a peak of 104 mph at the summit of Big Sky two nights ago (<strong><a href="https://www.mtavalanche.com/images/21/wind-transport-wolverine-peak">Wo… Peak wind-loading</a>,</strong> <a href="https://www.mtavalanche.com/images/21/snow-transport-lone-mountain"><st… Sky wind transport photo</strong></a>). Winds stripped some slopes of all available soft snow and deposited drifts 1-3’ deep on others. Drifted slopes avalanched naturally on <a href="https://mtavalanche.com/node/24768"><strong>Saddle Peak</strong></a> in the Bridger Range, near <a href="https://mtavalanche.com/node/24755"><strong>Maid of the Mist</strong></a> (<a href="https://www.youtube.com/watch?v=IWqFF8GE__g&amp;list=PLXu5151nmAvQDzKmH…;) in Hyalite Canyon, and on <a href="https://mtavalanche.com/node/24752"><strong>Iceberg Peak</strong></a> near Cooke City and under the weight of skiers on <a href="https://mtavalanche.com/node/24766"><strong>Miller Mountain</strong></a>. Avoid steep slopes with on-going wind-loading or large pillows of recently drifted snow where small to large avalanches are possible.</li>
<li><strong>Persistent weak layers near the ground:</strong> This weekend skiers triggered an 8-10’ deep avalanche near Mount Blackmore (<a href="https://www.mtavalanche.com/node/24732"><strong>photos and details</strong></a>), others observed a natural deep-slab avalanche near Flanders Creek (<a href="https://www.mtavalanche.com/images/21/natural-deep-slab-near-flanders">…;), and snowmobilers triggered an avalanche that broke near the ground in McAtee Basin (<a href="https://www.mtavalanche.com/node/24748"><strong>photo and details</strong></a>). These are the first three slides to break on sugary snow at the base of the snowpack since February. Slides like this are a low probability, high consequence event and avoiding steep, complex slopes is the safest management strategy until this layer has fully adjusted to recent loading.</li>
<li><strong>Weak interface under recent snow:</strong> A weak layer of near-surface facets formed on some slopes, but not all, and was buried under 2-4’ of snow during the last 10 days. Skiers triggered avalanches at the interface between the old and new snow 7-10 days ago on Mount Blackmore (<a href="https://mtavalanche.com/node/24676"><strong>photo and details</strong></a>), Alex Lowe Peak (<a href="https://mtavalanche.com/node/24673"><strong>photos and details</strong></a>), and Hyalite Peak (<a href="https://mtavalanche.com/node/24668"><strong>photos and details</strong></a>) and we found it on some slopes around Buck Ridge (<a href="https://www.youtube.com/watch?v=JZ1rnPsoIIg&amp;list=PLXu5151nmAvQDzKmH…;) and Cooke City (<a href="https://www.youtube.com/watch?v=CZ27CVuKWuA&amp;list=PLXu5151nmAvQDzKmH…;). It hasn’t been reacting recently, but it is worth digging down and performing a quick stability test at this interface before committing to any steeper terrain (<a href="https://www.youtube.com/watch?v=sqn0KFZqXYs&amp;list=PLXu5151nmAvQDzKmH… V</strong></a><a href="https://www.youtube.com/watch?v=sqn0KFZqXYs&amp;list=PLXu5151nmAvQDzKmH…;
</ol>

<p>Human-triggered avalanches are possible today and the avalanche danger is rated MODERATE.</p>

<p>If you get out, please send us your observations no matter how brief. You can submit them via our <a href="https://www.mtavalanche.com/node/add/snow_observation"><strong>website<…;, email (<a href="mailto:mtavalanche@gmail.com"><strong>mtavalanche@gmail.com</strong></a…;), phone (406-587-6984), or Instagram (#gnfacobs).</p>