17-18

<p>Storm totals are 14-18" in the Bridger and northern Gallatin Ranges, 10" around Big Sky, and 12" near Cooke City. In areas with the heaviest snowfall amounts, the snow water equivalent (<a href="https://www.nrcs.usda.gov/wps/portal/nrcs/detail/or/snow/?cid=nrcs142p2…;) measured 1-1.5”.</p>

<p>There is much to celebrate: lots of snow, great riding and skiing and mostly good stability. We have not received reports of avalanche activity and overall our snowpack has good structure and strength, which Eric shows in his <strong><a href="https://youtu.be/yqJ9-AsTwOQ">video</a></strong&gt; from the Bridger Range yesterday. However, there are a few isolated slopes with layers of weak snow found either at the ground or underneath the hard ice crust that formed during the Thanksgiving heat wave. Skiers in the northern Bridger Range on <a href="https://www.google.com/maps/d/edit?mid=18gJmy0S6HyEAGjuEHTcI38bRD94&amp… Throne</a> had a layer under the ice crust propagate in their stability test and decided to ski a different aspect. I found facets on the ground up Buck Ridge yesterday (<strong><a href="https://youtu.be/pOSSQJpkbRo">video</a></strong&gt;) and we cannot forget the deep avalanche that the ski patrol released near the summit of Lone Peak (<strong><a href="https://youtu.be/6Dueob5ScfI">video</a></strong&gt;) last Thursday. In order to navigate slopes with these rogue weak layers we need to dig and test before skiing in avalanche terrain.</p>

<p>Last night, strong westerly winds blew the new snow into slabs which will be easily triggered. These will be found near ridgelines and in lower elevation gullies. The wind and new snow also grew cornices, which I saw on Buck Ridge (<strong><a href="https://www.mtavalanche.com/images/17/buck-ridge-cornices">photo</a></s…;). Stay away from avalanche terrain with wind loads and avoid slopes underneath cornices. For today, the avalanche danger is<strong> CONSIDERABLE</strong> on slopes that are wind-loaded and <strong>MODERATE </strong>on other terrain.</p>

<p>The southern Madison Range and mountains around West Yellowstone received 6” of new snow. I was in Lionhead a week ago and found most slopes to be stable (<strong><a href="https://youtu.be/0d4B8XRu31c">video</a></strong&gt;) and capable of handling this new load. The area of concern are wind-loaded slopes near the ridgelines. Winds are blowing 15-25 mph out of the west creating wind slabs that will be possible to trigger. For today, the avalanche danger is <strong>MODERATE</strong> on wind-loaded slopes and <strong>LOW</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>A foot of snow in Hyalite yesterday totaled 1.1” of snow water equivalent (<strong><a href="https://www.nrcs.usda.gov/wps/portal/nrcs/detail/or/snow/?cid=nrcs142p2…;). In the Bridger Range and near Big Sky 10” of snow equaled .5” SWE, and near Cooke City snow since Friday totaled 1.2” SWE. Wind last night and today will drift new snow into 1-3 foot deep slabs that are easy to trigger. Near Cooke City, strong northwest wind formed slabs near ridgelines and along lower terrain like the edges of gullies and bases of cliffs. Yesterday, skiers near Cooke City backed off riding a steep couloir after they found a propagating wind slab in stability tests and heard a cornice break off a ridge nearby. Lower wind speeds near Bozeman and Big Sky will readily drift 10-12” of low density snow into slabs that are easy to trigger, located near ridgelines (<strong><a href="https://youtu.be/XOCjg5IKTsY">video</a></strong&gt;).</p>

<p>On non-wind loaded slopes, slabs of deep new snow are possible to trigger, and dry loose avalanches could run long distances on hard, supportable crusts underneath. Before travelling in steep terrain dig a couple feet to see how the new snow is bonding to the layers underneath, and watch for obvious signs of instability like cracking and collapsing and natural avalanches.</p>

<p>New snow and wind make avalanches easy to trigger today, and the avalanche danger is <strong>CONSIDERABLE</strong>. Avoid wind loaded slopes and carefully assess the snowpack before approaching steep terrain.</p>

<p>Aside from new snow and wind slabs the snowpack is generally stable and lacks widespread weak layers. A large avalanche triggered by Big Sky ski patrol on Thursday shows that isolated instabilities exist and large avalanches are not impossible (<a href="https://youtu.be/6Dueob5ScfI"><strong>video</strong></a&gt;, <a href="https://www.mtavalanche.com/images/17/n-summit-slide-crown"><strong>pho…;). On Saturday, skiers in Hyalite found old, weak snow near the ground breaking in stability tests and chose safer terrain for the day. It never hurts to do your homework before riding in steep terrain.</p>

<p>Near West Yellowstone and the southern Madison Range 4-6” of snow totaled .3-.5” SWE. Wind slabs will be possible to trigger near ridgelines, and could be 1-2 feet deep. On non-wind loaded slopes, the new snow is minimal weight on a generally stable snowpack and avalanches are not likely (<strong><a href="https://youtu.be/0d4B8XRu31c">video</a></strong&gt;). Approach wind loaded slopes with caution. The avalanche danger today is <strong>MODERATE</strong> on wind loaded slopes and <strong>LOW</strong> on non-wind loaded slopes.</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>