19-20

<p>Dave and I went to the <a href="https://www.mtavalanche.com/node/13952">Throne</a&gt; in the northern Bridger Range yesterday (<strong><a href="https://youtu.be/MlN6PWVKInI">video</a></strong&gt;). The wind was ripping at all elevations and blowing the couple inches of new snow into thin drifts, our primary avalanche concern. Strong winds have also fed cornices. These overhangs of snow came tumbling down on Buck Ridge (<u><strong><a href="https://youtu.be/VsPzWQjG5bY">video</a></strong></u><u&gt;, </u><u><strong><a href="https://www.mtavalanche.com/images/20/natural-cornice-collapse-2nd-yell…;) this past weekend, and triggered an avalanche last Wednesday in the Hourglass (a gulley north of Bridger Bowl) that broke in weak, sugary facets near the ground (<u><strong><a href="https://www.mtavalanche.com/images/20/hourglass-chute-crown">photo</a><…;). Last Friday we investigated a large slide that was triggered by a snowcat in a thin and weak snowpack near Swan Creek (<u><strong><a href="https://www.youtube.com/watch?v=mpWviZprZZM&amp;feature=emb_logo">video…;, <u><strong><a href="https://www.mtavalanche.com/node/22269">photo and details</a></strong></u>). Crumbly, sugary snow (depth hoar) on the ground avalanched as the groomer cleared the trail proving that thin snowpacks still harbor weak snow that a skier, rider or cornice could trigger. Skiers on Mt Ellis yesterday had poor stability test scores (ECTP13) in this bottom layer; more evidence of avalanche potential in areas with thin snow cover.</p>

<p>Wind drifts, cornices and weak facets at the ground are all partners in crime. When they team up, avalanches can happen. The travel advice today is simple: give cornices a wide berth, stay off of slopes if you get cracking in the wind-drifts and realize that facets at ground could break if you get unlucky. For today the avalanche danger is rated MODERATE on all slopes.</p>

<p>In the southern ranges, including the mountains around West Yellowstone and Cooke City, avalanche conditions are generally safe. Even though triggering avalanches is unlikely, wind has been blowing and a few thin wind drifts may crack and slide. Cornices are also growing and could break far back from their edge. Don’t temp these overhanging behemoths; gravity always wins. Avalanches are not impossible, just not expected. During times of relative stability due diligence is still required. Carry rescue gear, travel with a partner, assess the snowpack, and only expose one person at a time in avalanche terrain. These protocols have a long history of saving lives, even during times of stability. For today the avalanche danger is rated LOW.</p>

<p>If you get out, please send us your observations no matter how brief. You can fill out an <u><strong><a href="https://mtavalanche.us17.list-manage.com/track/click?u=6653a830e4819c9e…; target="_blank">observation form</a></strong></u>, email us (<u><strong><a href="mailto:mtavalanche@gmail.com&quot; target="_blank">mtavalanche@gmail.com</a></strong></u>), leave a VM at 406-587-6984, or Instagram (#gnfacobs).</p>

<p>In the northern ranges moderate to strong winds gusted up to 50 mph and 65 mph in Hyalite Canyon. These winds are building fresh drifts of snow and increasing the size of already enormous cornices. While the 1-3" of new snow won't add much widespread stress to the snowpack, it will provide ammunition for wind loading. Yesterday at Buck Ridge we triggered a 6” deep wind drift on a small test slope. We also observed a natural cornice collapse in Second Yellowmule. Avoid these behemoths as they can fail much farther back than expected (<a href="https://youtu.be/VsPzWQjG5bY"><strong>video</strong></a&gt;). Additionally, cornice collapses may trigger deeper avalanches on the slopes below. This story played out in the Hourglass Chute north of Bridger Bowl last Thursday (<a href="https://www.mtavalanche.com/images/20/hourglass-chute-crown"><strong>ph…;). Deep instabilities are less sensitive without a more significant load, but triggering avalanches on weak facets near the ground is still possible. We rode conservatively yesterday because of this possibility and less than a week ago a backcountry trail groomer triggered an avalanche on this layer that rolled the snowcat and driver 165 feet down the hill (<a href="https://www.youtube.com/watch?v=mpWviZprZZM&amp;feature=emb_logo"><stro…;, <a href="https://www.mtavalanche.com/node/22269"><strong>photo and details</strong></a>).</p>

<p>Today, avoid wind loaded slopes and cornices while maintaining a healthy fear of the less likely possibility of avalanches breaking on deeply buried weak layers. Human triggered avalanches are possible and the danger is MODERATE.</p>

<p>In the southern ranges and in the mountains around Cooke City moderate winds from the southwest to the west are creating new drifts of snow and increasing the size of cornices. These cornices can break far back from the edge resulting in a dangerous fall alongside school bus-sized blocks of snow and potentially triggering avalanches on slopes below. Today, wind drifts are especially concerning near high consequence terrain traps such as above trees, cliffs and gullies (<a href="https://youtu.be/9g-x7o56ek8"><strong>video</strong></a&gt;). It has been several weeks since we have received any reports of avalanches failing on deeply buried weak layers and stability continues to improve (<a href="https://youtu.be/2IzNvRo0R3w"><strong>video</strong></a&gt;). However, last Thursday skiers in the Southern Gallatin Range collapsed a slope that shifted an inch downhill before arresting. The skiers listened to the message and stayed in lower angle terrain (<a href="https://www.mtavalanche.com/node/22267"><strong>details</strong></a&gt;).</p>

<p>Minimize your exposure to wind loaded slopes with high consequence runouts, assess the snowpack and employ safe travel protocols when in avalanche terrain. Human triggered avalanches are unlikely and the danger is rated LOW.</p>

<p>If you get out, please send us your observations no matter how brief. You can fill out an&nbsp;<a href="https://mtavalanche.us17.list-manage.com/track/click?u=6653a830e4819c9e…; target="_blank"><strong>observation form</strong></a>, email us (<a href="mailto:mtavalanche@gmail.com&quot; target="_blank"><strong>mtavalanche@gmail.com</strong></a>), leave a VM at 406-587-6984, or Instagram (#gnfacobs).&nbsp;</p>