17-18

<p>Yesterday’s 7-9” of snow in the northern ranges and 3-6” of snow in the south will be blown into drifts from last night and this morning’s windy conditions. These drifts can be triggered today. Yesterday, skiers to the west of Cooke City triggered an avalanche (no one was caught) that broke under new, windblown snow (<strong><a href="https://www.mtavalanche.com/images/17/skier-triggered-avalanche-near-co…;, <strong><a href="https://www.mtavalanche.com/images/17/skier-triggered-avalanche-near-co…;) and another skier south of Cooke City found similar instability (<strong><a href="https://www.mtavalanche.com/images/17/sign-instability-woody-ridge">pho…;). Ridgetop winds have been westerly, but wind-loading may occur on many aspects since blowing snow does not always behave in an orderly way.</p>

<p>On some slopes it is possible to trigger an avalanche on a weak layer of facets buried 2-3 feet deep. I found this on Buck Ridge on Sunday (<a href="https://www.youtube.com/watch?v=ovxnh3oZPCA&amp;index=1&amp;list=PLXu51…;) and saw one avalanche on a wind-loaded slope to the south (<a href="https://www.mtavalanche.com/images/17/shedhorn-mountain-natural-avalanc…;). Overall instabilities are not widespread and will not last long, which Eric noted in Taylor Fork (<a href="https://www.youtube.com/watch?v=u7_Z88o2aaQ&amp;list=PLXu5151nmAvQSYtIf…;) and Alex found in Cooke City (<a href="https://www.youtube.com/watch?v=i_IKXNUrU5g"><strong>video</strong></a&…;). These facets are notably weaker in Lionhead, Bacon Rind (<a href="https://www.mtavalanche.com/images/17/small-avalanche-facets-near-bacon…;),the west side of the Bridger Range, and low elevation slopes; generally any area with a shallow snowpack.</p>

<p>Three steps to stay safe:</p>

<ol>
<li>Get caught up on all our recent <strong><a href="https://www.mtavalanche.com/photos">photos</a></strong&gt; and <strong><a href="https://www.youtube.com/playlist?list=PLXu5151nmAvQSYtIfyQP-gMYrlfja6Ls…; because seeing is believing.</li>
<li>Stay clear of wind-loaded slopes since avalanches are likely to be triggered. Cracking or collapsing are signs of dangerous conditions.</li>
<li>Dig 2-3’ deep to an ice layer that formed over Thanksgiving (you can’t miss it) and do a stability test. A clean break indicates instability.</li>
</ol>

<p>For today, the avalanche danger is rated <strong>CONSIDERABLE</strong> on all wind-loaded slopes and <strong>MODERATE</strong> on all others.</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 near West Yellowstone has an unstable snowpack&nbsp;and dangerous avalanche conditions exist. Two feet of snow last week formed a cohesive slab above a persistent weak layer of sugary facets (<a href="https://www.youtube.com/watch?v=Kl0SZcPkP4I&amp;index=2&amp;list=PLXu51…;). Even without new snow today, this unstable snowpack is sensitive to the weight of a snowmobiler or skier, and large, destructive avalanches are possible to trigger. For this reason, the avalanche danger today is <strong>CONSIDERABLE</strong> on all slopes. Be extra cautious of riding on or below slopes steeper than 30 degrees, and expose only one person at a time when riding or crossing below steep slopes.</p>

<p>In the mountains near Bozeman, Big Sky and Cooke City, moderate west-northwest wind drifted last week’s snow into slabs below ridgelines. Skiers in the Bridger Range were able to trigger 1-2 foot deep, 20 foot wide wind slabs yesterday, and these slabs are possible to trigger today. Be cautious of wind loaded slopes and cornices, and minimize exposure to high consequence terrain like steep slopes over cliffs.</p>

<p>Light snow and wind today will create small, fresh wind slabs that are minimal hazard alone, but add to larger slabs formed over the weekend. If Santa delivers more snow&nbsp;than expected, larger wind slabs could become easy to trigger. Avoid steep terrain if you see cracking and collapsing of the snowpack.</p>

<p>Secondary to wind slabs, there are some slopes where it is possible to trigger an avalanche on&nbsp;facets buried 2-3 feet deep. Doug found this layer below the new snow on Buck Ridge yesterday (<strong><a href="https://www.youtube.com/watch?v=ovxnh3oZPCA&amp;index=1&amp;list=PLXu51…;), and witnessed one avalanche on a wind loaded slope (<strong><a href="https://www.mtavalanche.com/images/17/shedhorn-mountain-natural-avalanc…;).&nbsp;This instability will not be a long-term problem and is not widespread (<a href="https://www.youtube.com/watch?v=i_IKXNUrU5g"><strong>video</strong></a&…;, <a href="https://www.youtube.com/watch?v=u7_Z88o2aaQ&amp;list=PLXu5151nmAvQSYtIf…;), but the weight of recent snow makes avalanches possible to trigger today. These facets are weaker in some areas like the west side of the Bridgers (<strong><a href="https://www.mtavalanche.com/images/17/unstable-test-results-west-side-b…;) and low elevation slopes that have a shallower snowpack (<a href="https://www.mtavalanche.com/images/17/natural-avalanche-cooke-city-1"><…;, <a href="https://www.mtavalanche.com/images/17/small-avalanche-facets-near-bacon…;). Avoid slopes where this layer is suspected, and dig 3 feet to test for this instability before riding steep terrain.</p>

<p>Today, avalanches are possible to trigger and the avalanche danger is <strong>MODERATE</strong> on all slopes. &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</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>Merry Christmas and Enjoy the Powder!</p>