17-18

<p>The equation is simple around Cooke City today. Heavy snow and strong winds are&nbsp;creating very dangerous avalanche conditions. Over the past 24 hours, Fisher Creek Snotel site has received close to a foot of snow totaling 1” of SWE. Snow amounts are higher at upper elevations. Yesterday, a skier got cracking and collapsing on lower elevation slopes near town. Skiers also triggered a few small avalanches a couple of days ago (<a href="https://www.mtavalanche.com/images/17/skier-triggered-avalanche-near-co…;, <a href="https://www.mtavalanche.com/images/17/sign-instability-woody-ridge"><st…;). These are obvious signs the snowpack is having trouble adjusting to the heavy load.</p>

<p>Today, continued snow and wind will create a perfect recipe for avalanches. All wind loaded slopes and avalanche run out zones should be avoided. Steeper, non-wind loaded slopes should be evaluated carefully and approached with caution.</p>

<p>Today, natural and human triggered avalanches are likely on wind loaded slopes which have a <strong>HIGH</strong> avalanche Danger. Non-wind loaded slopes have <strong>CONSIDERABLE</strong> avalanche danger.</p>

<p>Wind is the dominating factor in the mountains around Bozeman, Big Sky and West Yellowstone. Overnight, winds blew 20-40 mph out of the west, with gusts around Hyalite and Big Sky breaking 50 mph. These strong winds combined with 3-5” of new snow will make wind slabs today’s primary avalanche concern.</p>

<p>Thick, dense slabs will be most likely below upper elevation ridgelines leeward to west winds (<a href="https://www.mtavalanche.com/images/17/shedhorn-mountain-natural-avalanc…;). These slabs will be 1-3’ thick and will easily fail under the weight of a skier and rider. Wind slabs will also be found on the leeward side of cross loaded terrain features on mid to low elevation slopes. Yesterday, skiers on Mt Blackmore in the northern Gallatin Range observed active wind transport in the bowl well below the summit. Today, avoiding wind loaded slopes will be the best way to avoid avalanches.</p>

<p>In addition to wind loaded slopes, a layer of facets buried 2-3’ remains a concern. This layer is most widespread in the mountains around West Yellowstone, but has sporadic distribution across the advisory area (<a href="https://www.youtube.com/watch?v=u7_Z88o2aaQ&amp;list=PLXu5151nmAvQSYtIf…;, </strong><a href="https://www.youtube.com/watch?v=ovxnh3oZPCA&amp;index=1&amp;list=PLXu51…;). Yesterday, a snowmobiler driving over Targhee Pass observed a recent slide on a small slope just off the road. Small slides are key indicators that larger slides are possible. It’s worth digging 2-3’ feet deep to assess this layer of facets before committing to steeper terrain.</p>

<p>Today, human triggered avalanches are 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>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>A southwest flow is bringing snow to Cooke City and the Lionhead area today. In the last week, 2-3’ of new snow outside Cooke City has been blown into wind drifts, with a few wind-loaded slopes triggered by skiers (<strong><a href="https://www.mtavalanche.com/images/17/skier-triggered-avalanche-near-co…;, <a href="https://www.mtavalanche.com/images/17/sign-instability-woody-ridge"><st…;). On some slopes, underneath this new snow is a weak layer of unstable facets. Skiers on Christmas Day triggered a small soft slab avalanche on a SW facing slope below treeline on this layer (<strong><a href="https://www.mtavalanche.com/images/17/skier-triggered-slide-hayden-cree…;). Last Friday and Saturday Alex investigated the snowpack and outlined these concerns in his <a href="https://www.youtube.com/watch?v=i_IKXNUrU5g"><strong>video</strong></a&…;, which is still relevant today.</p>

<p>In the Lionhead area, 2’ of snow in the past 7 days fell onto weak, sugary facets that are showing signs of instability (<a href="https://www.youtube.com/watch?v=Kl0SZcPkP4I&amp;index=2&amp;list=PLXu51…;). Forecasted snowfall and wind will make this layer reactive to human triggering.</p>

<p>Most avalanches occur during or immediately after a storm and the next few days will be unstable; wind-loaded slopes especially so. Turn around at the first signs of cracking or collapsing and be aware that recent avalanches are Mother Nature’s warning sign that nearby slopes are also unstable. For today, the avalanche danger is <strong>CONSIDERABLE</strong> on wind-loaded slopes and <strong>MODERATE</strong> on all others, but will rise to <strong>CONSIDERABLE </strong>on all slopes if/when the storm hits.</p>

<p>In the last week close to 2’ of snow fell in the Bridger, Gallatin and Madison Ranges. Strong ridgetop winds loaded slopes, but overall avalanche activity was minimal and the snowpack was strong enough to handle the new load, which Eric found last Thursday in Taylor Fork (<a href="https://www.youtube.com/watch?v=u7_Z88o2aaQ&amp;list=PLXu5151nmAvQSYtIf…;). Skiers up Mt. Blackmore yesterday only saw loose snow slides and found no deeper instabilities (<strong><a href="https://www.mtavalanche.com/images/17/loose-snow-sluffs-mt-blackmore">p…;). There are always exceptions, and on Sunday I found a thin layer of weak facets breaking in my stability tests (<a href="https://www.youtube.com/watch?v=ovxnh3oZPCA&amp;index=1&amp;list=PLXu51…;) and I could see an avalanche far to the south on a wind-loaded slope (<a href="https://www.mtavalanche.com/images/17/shedhorn-mountain-natural-avalanc…;). These instabilities are isolated, but worth looking for. Dig 2-3’ deep to the prominent ice crust and test the snow because just one unstable slope would ruin your day.</p>

<p>Human triggered avalanches are possible today, most surely on wind-loaded slopes, but also on slopes that harbor a weak layer of facets 2’ under the new snow. The danger is rated <strong>MODERATE</strong> on all slopes today.</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>