17-18

<p>Stability is generally good across the advisory area. There is little in the way of buried persistent weak layers and the snowpack has not endured significant loading over the past few days (<a href="https://youtu.be/moz6PkFpAe0"><strong>video</strong></a&gt;). The biggest avalanche concern today is wind drifted snow near the ridgelines. Steady west winds throughout the week have formed drifts 1-2’ thick on leeward slopes (<a href="https://www.mtavalanche.com/images/17/skier-triggered-wind-slab-hyalite…; <a href="https://www.mtavalanche.com/images/17/wind-slab-cooke-city"><strong>pho…;). These drifts shouldn’t be overly sensitive to human triggers, but I still wouldn’t trust them, especially in steeper high consequence terrain. It should be easy to recognize and avoid wind loaded slopes today, which will be the best way to avoid triggering a slide.</p>

<p>Although we have the pleasure of enjoying a mostly stable snowpack, a massive avalanche at Big Sky Ski Resort yesterday highlights the fact that not all is perfect (<a href="https://youtu.be/0d4B8XRu31c"><strong>video</strong></a&gt;, <a href="https://www.mtavalanche.com/images/17/lionhead-facets"><strong>facets photo</strong></a>). This slide occurred on the North Summit Snowfield during control work and created a crown up to 10’ feet deep. It failed on depth hoar that formed from the snow that fell in September. The slide broke 500 vertical feet above the shot that triggered it producing an impressive display of propagation. This avalanche ran full path and broke mature trees in the run out zone. While this slide isn’t highly representative of the overall snowpack, it’s a good reminder of what remains possible.</p>

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

<p>The snowpack took multiple steps backwards during the warm weather around Thanksgiving. Since then, intermittent storms and below freezing temps have helped the snowpack recover. Since Monday, 4-8” of snow has fallen in most mountain locations. This new snow has been transported by strong westerly winds, which loaded slopes at many elevations. Today, wind loaded slopes will be primary avalanche concern.</p>

<p>On Tuesday, a skier up Hyalite triggered a small avalanche 1’ deep and 25’ wide on a slope well below the ridgeline (<a href="https://www.mtavalanche.com/images/17/skier-triggered-wind-slab-hyalite…;). He also noted large cornices, which are clear indicators of wind loading (<a href="https://www.mtavalanche.com/images/17/wind-loading-and-large-cornices-h…;). A skier outside of Cooke City also triggered a small wind slab yesterday in high alpine terrain (<strong><a href="https://www.mtavalanche.com/images/17/wind-slab-cooke-city">photo</a></…;). Winds have dropped over the past 24 hours, but recently formed wind slabs could still be triggered by skiers or riders. It’s important to remember that even small slides can be dangerous, especially in steep high consequence terrain.</p>

<p>Besides new snow and wind-loading the underlying snowpack is mostly stable. On Tuesday my partners and I skied Saddle Peak in the Bridger Range and found mostly stable conditions (<a href="https://youtu.be/moz6PkFpAe0"><strong>video</strong></a&gt;). Our biggest concern was wind slabs along the ridgeline. Doug rode into Lionhead on the same day and found similar conditions, with the exception of one pit that produced unstable results on a layer or facets near the ground (<a href="https://youtu.be/0d4B8XRu31c"><strong>video</strong></a&gt;, <a href="https://www.mtavalanche.com/images/17/lionhead-facets"><strong>facets photo</strong></a>). This layer is not widespread and shouldn’t last long. However, finding it illustrates the need to dig and test even when the snowpack is generally stable.</p>

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

<p>Today’s avalanche concern involves wind and new snow. Last night, gusts of 50-70 mph with strong, steady winds have loaded slopes at many elevations, not just the ridgelines. Snowfall from Monday morning and this morning will drift into wind slabs that could be triggered. Yesterday, a skier up Hyalite triggered a small avalanche 1’ deep and 25’ wide on a slope well below the ridgeline (<strong><a href="https://www.mtavalanche.com/images/17/skier-triggered-wind-slab-hyalite…;). He also noted cornices growing quite large for this early in the season (<strong><a href="https://www.mtavalanche.com/images/17/wind-loading-and-large-cornices-h…;). Cornices are a sign of wind-loading and are also triggers for avalanches when they break. Wind-loaded slopes should be approached carefully. Recent avalanches, cracking and collapsing are warning signs to stay out of avalanche terrain.</p>

<p>Besides new snow and wind-loading the underlying snowpack is mostly stable. We are still gathering our first field data, but all findings are similar: there is no widespread weak layer buried in the snowpack. Eric was on Saddle Peak in the Bridger Range yesterday and found stable conditions (<strong><a href="https://youtu.be/moz6PkFpAe0">video</a></strong&gt;). I rode into Lionhead yesterday and found mostly stable snow, but got lucky in my search for instability and dug on a slope with a layer of weak snow on the ground that broke in my stability tests (<strong><a href="https://youtu.be/0d4B8XRu31c">video</a></strong&gt;, <strong><a href="https://www.mtavalanche.com/images/17/lionhead-facets">facets photo</a></strong>, <strong><a href="https://www.mtavalanche.com/images/17/lionhead-ridge-pit">pit photo</a></strong>). I was surprised to see this. This layer was moist, only 5 cm thick and will likely not last long. However, finding it illustrates the need to dig and test even during times of stability.</p>

<p>This morning’s snowfall and strong winds make avalanches possible and a <strong>MODERATE</strong> avalanche danger throughout our entire advisory area.</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>