17-18

<p>Overall stability is improving around Cooke City, but new snow and wind will keep conditions spicy today, primarily on wind loaded slopes. Over the past 24 hours, consistent winds of 20-40 mph winds have impacted this area. Today, the primary concern is slides failing in the new snow. Wind drifts 1-2’ feet deep will be easy to trigger, mainly on wind loaded slopes near ridgelines or cross loaded sub-ridges. Slides failing on instabilities deeper in the pack are becoming less likely, but still remain a concern (<a href="https://www.mtavalanche.com/images/18/natural-avalanche-near-republic-p…;, <strong><a href="https://www.mtavalanche.com/photos">photo</a></strong&gt;). Last Saturday, a snowmobiler was buried in an avalanche he triggered in Sheep Creek (<a href="https://youtu.be/NiS2tJ-o7Nw"><strong>video</strong></a&gt;). Luckily he was uncovered quickly when his partners found his finger sticking out of the snow. Triggering slides like this is becoming less likely, but not impossible.</p>

<p>Today, human triggered avalanches are likely today 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>Today’s combination of steady winds and fresh snow available for transport will result in sensitive, fresh wind drifts. This problem will be mostly confined to upper elevation slopes leeward to westerly winds. Watch for wind drifts and pillows near ridgelines and avoid slopes that appear to be freshly wind loaded. Slides will likely stay confined to the new snow, but do have the potential to step down to older wind drifts that formed prior to this storm. Loose snow avalanches involving the new snow are also possible on steeper slopes.</p>

<p>Outside of new snow instabilities, the snowpack is generally stable. Yesterday, we traveled to Mt Ellis and found a deep and strong snowpack. This is representative to what we’re seeing in the mountains around Bozeman and Big Sky (<a href="https://youtu.be/GOpY8hRn4iM"><strong>video</strong></a><strong&gt;, </strong><a href="https://youtu.be/aNR2eKmlU4U"><strong>video</strong></a&gt;).</p>

<p>Today, sensitive wind drifts make human triggered avalanches 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>Yesterday, a fresh human triggered slide was observed up Cabin Creek in the southern Madison Range. Details and slim, but the slide was triggered by snowmobilers or snowbikers on a steep, wind loaded slope. It sounds like no one was injured in the event. The slide likely failed on a layer of surface hoar that has been found throughout the southern mountains. Today, 6-8” of new snow combined with moderate to strong winds out of the west will form fresh wind drifts and add stress to this buried weak layer.</p>

<p>Wind drifts will be sensitive to human triggers today. For this reason the avalanche danger is rated <strong>CONSIDERABLE</strong> on wind loaded slopes. The buried surface hoar layer does not have a widespread distribution, but does exist in isolated areas (<a href="https://www.mtavalanche.com/images/18/surface-hoar-stripe-pit"><strong>…;, <a href="https://youtu.be/vC1Z1rae2uE"><strong>video</strong></a&gt;). This makes human triggered slides possible on non-wind loaded slopes which have <strong>MODERATE </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>Yesterday, Cooke City was windy and snow was blowing at the ridgelines and across faces loading slopes and drifting snow. Triggering a slide on these wind slabs is a concern. Cornices grew with the last storm and these monsters could break off, steamroll and injure you, or worse, trigger a deep and large avalanche that would be deadly (<strong><a href="https://www.mtavalanche.com/images/18/natural-avalanche-near-republic-p…;, <strong><a href="https://www.mtavalanche.com/images/18/natural-avalanche-near-republic-p…;). Furthermore, on Saturday, a snowmobiler was buried in an avalanche he triggered in Sheep Creek (<a href="https://youtu.be/NiS2tJ-o7Nw"><strong>video</strong></a&gt;). Luckily he was uncovered quickly when his partners found his finger sticking out of the snow. Triggering slides like this is becoming less likely, but not impossible. For today, the avalanche danger is rated <strong>MODERATE</strong> on all slopes.</p>

<p>The northern mountains have been windy at all elevations and aspects for a few days creating drifts at ridgelines and in gullies. Instabilities associated with these drifts are isolated and small. One other concern associated with wind are cornices breaking underfoot since these thickened with the last storm and hide the ridge crest. The snowpack is generally strong and stable which is what Eric found in the Bridger Range on Friday (<a href="https://youtu.be/GOpY8hRn4iM"><strong>video</strong></a&gt;) and Alex in Beehive on Sunday (<a href="https://youtu.be/aNR2eKmlU4U"><strong>video</strong></a&gt;). Conditions have only improved since their visits. Avalanches are unlikely today, and the danger is rated <strong>LOW</strong>.</p>

<p>A weak layer of surface hoar can be found in the southern Madison and southern Gallatin Ranges and near West Yellowstone. These feathery crystals (<a href="https://www.mtavalanche.com/images/18/surface-hoar-crystal"><strong>pho…;) are buried up to 2 feet deep, are gaining strength, and becoming hard to trigger. Alex rode into the Lionhead area and could see it as a gray stripe in the snowpack (<a href="https://www.mtavalanche.com/images/18/surface-hoar-stripe-pit"><strong>…;, <strong><a href="https://youtu.be/vC1Z1rae2uE">video</a></strong&gt;). This layer is mostly unreactive and avalanches are improbable, but it’s still our biggest worry. For today, the avalanche danger is rated <strong>LOW</strong> on all slopes.</p>