17-18

<p>The Bridger Range got completely missed by the weak storm that impacted the mountains south of Bozeman. The snowpack is generally stable and likelihood of triggering a slide is low. The main concern in the Bridger Range is large cornices. Give these monsters amply distance along the ridgelines and limit&nbsp;exposure time&nbsp;on slopes below (<a href="https://youtu.be/yaCiK8VlwwA"><strong>video</strong></a&gt;, <a href="https://www.mtavalanche.com/images/18/large-cornices-bridger-range"><st…;).</p>

<p>Today, natural and human triggered avalanches are unlikely and the avalanche danger is rated <strong>LOW</strong>.</p>

<p>A fast-moving storm dropped 2-4” of snow in the mountains south of Bozeman including Cooke City. This quick shot of snow was accompanied by winds gusting 40+ mph out of the W-SW. The combination of new snow and strong winds formed fresh wind slabs in upper elevation terrain.</p>

<p>Today, wind slabs will be the primary avalanche concern (<strong><a href="https://www.mtavalanche.com/images/18/skier-triggered-wind-slab">photo<…;). Fresh drifts will be possible to trigger, primarily on the leeward side of upper elevation ridgelines and cross loaded sub-ridges. Watch for and avoid areas of wind drifted snow, especially in steep, higher consequence terrain.</p>

<p>A less likely but more dangerous problem is slides failing on weak layers buried 2-3’ deep. On Wednesday, a snowmobiler up Red Canyon north of West Yellowstone triggered and was caught in a large persistent slab avalanche. He deployed his airbag and fortunately wasn’t buried. The slide broke 2-3’ deep, 2-300’ wide and occurred on a southwest facing slope. A similar slide occurred yesterday near Mt Jefferson in the Centennial Range. These are the first persistent slab avalanches reported in weeks. Although buried persistent weak layers are not a widespread problem, they do exist is isolated areas. It’s always worth digging to assess the snowpack structure before jumping into avalanche terrain (<a href="https://youtu.be/0jpDHOgb7Hs"><strong>video</strong></a&gt;).</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> avalanche 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 across the advisory area is generally stable (<a href="https://youtu.be/0jpDHOgb7Hs"><strong>video</strong></a&gt;). Minimal snow and wind over the past few days and the lack of a buried persistent weak layers has decreased the likelihood of triggering avalanches. However, there remains a slight possibility that skiers or riders could trigger isolated pockets of unstable snow, primarily on steep slopes wind loaded earlier in the week. A slide near Bacon Rind on Tuesday is a good illustration of this isolated problem (<a href="https://www.mtavalanche.com/images/18/skier-triggered-wind-slab"><stron…;).</p>

<p>It’s unlikely that a slide would break more than 1-2’ deep or propagate over a wide area, but it’s important to remember that even small slides can have severe consequences. Also, keep large cornices on the radar (<a href="https://www.mtavalanche.com/images/18/large-cornices-bridger-range"><st…;). These can break far back from the ridge and trigger avalanches on slopes below. Cornices were our main concern in the Bridger Range on Tuesday (<a href="https://youtu.be/yaCiK8VlwwA"><strong>video</strong></a&gt;).</p>

<p>For today, triggering avalanches is unlikely and the danger is rated <strong>LOW</strong>. The definition of Low includes “small avalanches in isolated areas or extreme terrain”, so stay safe by staying smart.</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>Without new snow or wind-loading, the likelihood of triggering avalanches is decreasing. Yesterday, a skier triggered a very small and thin avalanche in the new snow around Cooke City (<strong><a href="https://www.mtavalanche.com/images/18/small-skier-triggered-avalanche">…;), and another party triggered a wind-loaded pocket in a gully near Bacon Rind on the east side of the highway (<strong><a href="https://www.mtavalanche.com/images/18/skier-triggered-wind-slab">photo<…;). These instabilities are isolated and will be even more difficult to trigger today. Yesterday, I rode and skied up Buck Ridge south of Big Sky and found stable snow (<strong><a href="https://youtu.be/0jpDHOgb7Hs">video</a></strong&gt;) which is also what Eric found in the Bridger Range.</p>

<p>Even with generally stable and safe conditions, avalanches are not impossible to trigger. Today there are three things to remember:</p>

<ol>
<li><strong>Cornices</strong> are huge (<strong><a href="https://www.mtavalanche.com/images/18/large-cornices-bridger-range">pho…;) and will break far from the edge, triggering a slope and/or crushing you along the way. Eric’s <strong><a href="https://youtu.be/yaCiK8VlwwA">video</a></strong&gt; from his trip to the Bridger Range yesterday highlights this danger.</li>
<li>Above freezing temperatures will melt the top few inches of low-density powder and create <strong>wet-loose avalanches</strong>, also known as point release slides. These will be on steep, south-facing slopes getting full sunshine. They will not be big, but they may knock you over, twist a knee, or push you off a cliff. Pinwheels of snow are a sign the snow is getting wet enough to slide.</li>
<li>Previously <strong>wind-loaded</strong> slopes may have small pockets that could avalanche.</li>
</ol>

<p>For today, triggering avalanches in unlikely and the danger is rated <strong>LOW</strong> on all slopes in our advisory area. The definition of Low includes “small avalanches in isolated areas or extreme terrain”, so do not turn off your brain.</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>