17-18

<p>The snowpack in the Lionhead area remains untrustworthy. Weak, sugary facets buried 2-3’ deep still hold the potential to propagate a fracture and produce large slab avalanches (<a href="https://youtu.be/taPrFLj52aA"><strong>video</strong></a><strong&gt;, </strong><a href="https://www.mtavalanche.com/images/18/snowmobile-triggered-avalanche-li…;). Terrain management is the best defense against triggering slides under these types of conditions. Avoiding steep slopes and low angle terrain connected to steeper slopes is a sure fire way to avoid triggering&nbsp;a slide. Although avalanches are becoming harder to trigger without new snow, dangerous avalanche conditions still exist.</p>

<p>For this reason the avalanche danger is rated <strong>CONSIDERABLE </strong>on all slopes.</p>

<p>Signs of instability such as cracking/collapsing and recent avalanches remain present in the mountains around Cooke City. On Tuesday, separate parties skiing west of Cooke City each got large collapses and one party observed an avalanche that likely released during the day (<a href="https://www.mtavalanche.com/images/18/unstable-snow-avalanche-and-colla…;). These are Mother Nature’s clues that avalanches are still possible. The tricky part about this area is many slopes are stable, but a few are not (<a href="https://www.mtavalanche.com/images/18/fin-avalanche1"><strong>photo</st…;). The easiest way to stay out of trouble is to avoid steep slopes altogether. If you do venture into avalanche terrain, assess the snowpack carefully and take the necessary time to make smart and informed decisions.</p>

<p>For today, human triggered avalanches are possible and the avalanche danger is <strong>MODERATE</strong>.</p>

<p>The primary avalanche problem in the mountains around Bozeman and Big Sky will be wind loaded slopes. Overnight, strong winds transported snow below upper elevation ridgelines. Wind slabs should be stubborn, but still hold the potential to fail with the proper trigger. Watch for and avoid wind loaded slopes if you’re traveling in steep, upper elevation terrain (<strong><a href="https://www.mtavalanche.com/photos">photo</a></strong&gt;).</p>

<p>A secondary concern will facets sitting over the Thanksgiving ice crust. This problem is not widespread and appears to be confined to slopes with a shallower snowpack. Yesterday, I skied north of Big Sky and found a poor snowpack structure on mid-elevation slopes around 8,000 ft. We did not experience any signs of instability, but did get unstable results in stability tests (<strong><a href="https://www.youtube.com/watch?v=Z5zkCJfIfdI">video</a></strong&gt;). This indicates this layer could still be a problem with the weight of new and wind-blown snow.</p>

<p>Something else to look out for will be a fresh layer of surface hoar and near surface facets (<strong><a href="https://www.mtavalanche.com/images/18/surface-hoar">photo</a></strong&gt;). These layers formed during the recent dry spell and could be a problem when buried by new snow. The distribution of these layers is unclear, but it will be something to keep in mind once more snow falls.</p>

<p>Today, human triggered avalanches are possible and the avalanche danger is rated <strong>MODERATE</strong>.</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 Lionhead area has weak and unstable snow near the ground (<a href="https://youtu.be/taPrFLj52aA"><strong>video</strong></a&gt;) that will take a long time to strengthen. One week ago we issued an avalanche warning for the area and on most days we received reports of avalanches or collapsing/cracking. Snowmobilers triggered slides on Sunday, one in Airplane Bowl, a popular spot on the east side of Lionhead Ridge (<a href="https://www.mtavalanche.com/images/18/snowmobile-triggered-avalanche-li…;), and another lower down in the trees (<a href="https://www.mtavalanche.com/images/18/remote-triggered-slide-near-lionh…;). It has been 4 days without new snow and the likelihood of triggering slides is decreasing, but the snow is still dangerous. For today, human triggered avalanches are likely and the avalanche danger is rated <strong>CONSIDERABLE</strong>.</p>

<p>Separate parties skiing west of Cooke City each got large collapses yesterday, possibly on the Thanksgiving crust buried 4+’ deep. One of them saw an avalanche that likely released during the day (<strong><a href="https://www.mtavalanche.com/images/18/unstable-snow-avalanche-and-colla…;). Words like "tricky", “untrustworthy”, and “wary”, are being used to describe the conditions. In some instances there are no immediate signs of instability on the approach or in a pit, yet an avalanche occurs nearby or the slope collapses with a heart-stopping “whumph”. The snowpack isn't overly poor, nor is it really good, it's in-between; some slopes are stable, but a few are not (<a href="https://www.mtavalanche.com/images/18/fin-avalanche1"><strong>photo</st…;). There are only a couple tried-and-true methods to keep us safe, the easiest one is to avoid steep slopes. The second is to dig and test multiple times if we think the slope is stable. The goal to find unstable snow <em>before</em> we commit to a slope. For today, the avalanche danger is <strong>MODERATE</strong> since it remains possible to trigger avalanches.</p>

<p>The snowpack is adjusting to last week’s 2-4 feet of new snow. Signs of instability, like collapsing and cracking are decreasing and test scores in snowpits are climbing higher. Slopes with a thin snowpack (less than 3’ deep) will be the most unstable (Dudley Creek <strong><a href="https://www.mtavalanche.com/images/18/skier-triggered-slide-dudley-cree…;) along with slopes near ridgelines that have an extra burden from wind-loading (<strong><a href="https://www.mtavalanche.com/images/18/natural-avalanche-argentina-bowl"…;). There also may be a lingering instability at the new/old snow interface plus weak, faceted snow mid-pack, which Alex describes in his <a href="https://youtu.be/QMEdLpX2oDs"><strong>video</strong></a&gt; from Sunday. In general, the snowpack is getting stronger and the avalanche danger is rated <strong>MODERATE</strong>.</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>