17-18

<p>November is three days young, but the snowpack could imply it is late December. There is up to four feet of snow on the ground in higher elevations near Bozeman and Cooke City, with 1-3 feet near Big Sky and West Yellowstone. Since Tuesday, the Bridger Range, Hyalite, and Cooke City received 20-26” of snow equal to 2-2.5” of snow water equivalent (<strong><a href="http://www.or.nrcs.usda.gov/snow/about/swe.html">SWE</a></strong&gt;); and the mountains near Big Sky and West Yellowstone got 4-8” of snow equal to .4-.8” of SWE.</p>

<p>Wind has drifted recent snow into slabs that are large enough to bury or injure a person if triggered. Wind slabs could be 2-3 feet thick in areas that received more snow. These drifts are likely near ridgelines and on steep, convex terrain. Avoid steep terrain that appears freshly loaded with dense drifts. Even smaller slides can be deadly if they pile deep in a confined gully or creek bed, or if they push a person through trees or over rocks. Many of these terrain traps are prominent right now due to still relatively thin snow cover.</p>

<p>New snow and wind slabs lie over a variety of surfaces ranging from old snow to previously bare ground (<strong><a href="https://www.youtube.com/watch?v=WfCdHe8cqu0&amp;list=PLXu5151nmAvQSYtIf…;). Avalanches are more likely where fresh slabs formed over old snow, and possible on any slope with enough snow to ski. Slopes that held snow prior to this storm also hold the best skiing, so dig a snowpit to assess stability before travelling into steeper terrain. Two days ago, skiers near Cooke City got unstable, propagating stability test results below the new snow (<strong><a href="https://www.mtavalanche.com/images/17/snow-pit-near-cooke">photo</a></s…;, <strong><a href="https://www.mtavalanche.com/images/17/miller-ridge-profile">snowpit</a>…;). This is a sign to avoid steeper terrain with a similar snowpack for now.</p>

<p>We have had a month and a half of steady snow, but&nbsp;many folks are probably heading out for the first time this season. Check all your gear (fresh batteries), check your partners’ gear, pay close attention to signs of instability such as cracking/collapsing, and carefully assess each slope before committing to steep terrain.</p>

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<p>If you get out and have any avalanche or snowpack observations to share, drop a line via our website, email (<a href="mailto:mtavalanche@gmail.com">mtavalanche@gmail.com</a&gt;), phone (406-587-6984), or Instagram (#GNFACobs).</p>

<p>The first official day of winter is still seven weeks away, but Mother Nature doesn’t seem to care. As snow amounts continue to rise, so will the enthusiasm to hit the backcountry. If you are getting out, keep in mind there are plenty of hazards lurking in the backcountry. As we know from the tragic event earlier this season (<a href="https://www.mtavalanche.com/sites/default/files/accident-reports/2017-1… report</a>), it does not take a large slide to create severe consequences. In fact, avalanches can be exceptionally dangerous early season due to the likelihood of impacting trees, rocks and other immovable objects.</p>

<p>Over the next few days, the primary avalanche concern will be wind loaded slopes. Moderate to strong winds out the west-southwest will form meaty slabs below ridgelines or cross loaded terrain features. These slabs will likely be touchy to human triggers and all wind loaded slopes should be approached with caution. While wind slabs are the main problem, non-wind loaded slopes also hold the potential to produce avalanches. The new snow is falling on a variety of old snow surfaces, some of which could produce unstable conditions (<a href="https://www.mtavalanche.com/images/17/high-north-northern-gallatin-rang…;, <a href="https://www.youtube.com/watch?v=WfCdHe8cqu0&amp;list=PLXu5151nmAvQSYtIf…;). Pay close attention to signs of instability such cracking/collapsing and carefully assess each slope before committing to steep terrain.</p>

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<p>If you get out and have any avalanche or snowpack observations to share, drop a line via our website, email (<a href="mailto:mtavalanche@gmail.com">mtavalanche@gmail.com</a&gt;), phone (406-587-6984), or Instagram (#GNFACobs).</p>