20-21

<p>Since Friday, the mountains received 15-23” of new snow equal to 1.4-1.8” of <a href="https://www.nrcs.usda.gov/wps/portal/nrcs/detail/or/snow/?cid=nrcs142p2… water equivalent</a> (SWE). Winds have been strong enough to transport snow at higher elevations and near ridgelines but overall have remained light to moderate through the storm. Avalanches today are all about the interface between the old and new snow. The snow fell onto an ice crust or a wet snow surface on many slopes and is bonding well. However, on some slopes that stayed cool during the March warm-up, new snow fell onto a thin, weak layer of near-surface facets. On Sunday, separate groups of skiers unintentionally triggered two avalanches in Hyalite Canyon. One was a close call that carried a skier several hundred feet down the mountain (<a href="https://mtavalanche.com/node/24673"><strong>Alex Lowe Peak details and photos</strong></a>, <a href="https://mtavalanche.com/node/24676"><strong>Mount Blackmore details</strong></a>). In Beehive Basin, a group triggered several loose snow avalanches or sluffs that would be hazardous in technical terrain (<a href="https://mtavalanche.com/node/24678"><strong>details and photo</strong></a>). On Saturday, skiers triggered a thin avalanche near Hyalite Peak that broke 150’ away from them and 150’ wide (<a href="https://www.mtavalanche.com/node/24668"><strong>photo and info</strong></a>).</p>

<p>Stack the deck in your favor by following safe travel protocols and assessing this interface with quick snowpits, each taking less than 2-minutes, as I demonstrate in my 59-second <a href="https://www.youtube.com/watch?v=sqn0KFZqXYs"><strong>video</strong></a&…;. Expect changes at different elevations and aspects, so dig more shallow pits rather than one deep one. Watch our recent field videos from <a href="https://youtu.be/zCKlHstJTqc"><strong>McAtee Basin</strong></a>, the <a href="https://www.youtube.com/watch?v=TAWRM8yRgUM&amp;list=PLXu5151nmAvQDzKmH… </strong></a>and <a href="https://www.youtube.com/watch?v=U1b5LjWLTac&amp;list=PLXu5151nmAvQDzKmH…; Ranges, and <a href="https://www.youtube.com/watch?v=VQd7lPN6zTQ&amp;list=PLXu5151nmAvQDzKmH… City</strong></a> for examples of where we found this layer.</p>

<p>Avalanches failing deeper than the interface are unlikely; however, the snow is stacking up. If you trigger a slide at the interface, now pushing 2’ deep, it is possible for it to step-down into older weak layers.</p>

<p>Today, human-triggered avalanches are possible, and the danger is rated MODERATE.</p>

<p>If you get out, please send us your observations no matter how brief. You can submit them via our <a href="https://www.mtavalanche.com/node/add/snow_observation"><strong>website<…;, email (<a href="mailto:mtavalanche@gmail.com"><strong>mtavalanche@gmail.com</strong></a…;), phone (406-587-6984), or Instagram (#gnfacobs).</p>

<p>Since Friday, the mountains received 10-17” of heavy snow, equal to 0.9-1.6” of <a href="https://www.nrcs.usda.gov/wps/portal/nrcs/detail/or/snow/?cid=nrcs142p2… water equivalent</a> (SWE). Winds increased to 10-20 mph from the west to southwest, transporting soft snow into unstable drifts. Our primary avalanche concerns today exist within this new and wind drifted snow. Yesterday, a group of skiers triggered an avalanche that broke 10” deep about 150’ above them, catching one person and carrying them 250 vertical feet down Alex Lowe Peak (<a href="https://mtavalanche.com/node/24673"><strong>details and photos</strong></a>). As they returned to the trailhead, they saw another group trigger an avalanche on the east face of Mount Blackmore (<a href="https://mtavalanche.com/node/24676"><strong>details</strong></a&gt;). Thankfully, no one was injured in either event, but it was a close call. On Saturday, a group near Hyalite Peak triggered a 4” deep, 150’ wide avalanche from 150’ away (<a href="https://www.mtavalanche.com/node/24668"><strong>photo and info</strong></a>). While small relative to February’s deep slab avalanches, none of these slides should be underestimated especially in steep or extreme terrain.</p>

<p>Assess the stability of the interface between old and new snow by digging down 2’ and performing quick extended column tests remembering that it will change at different aspects and elevations. Yesterday at Buck Ridge, we found a weak layer of near-surface facets that consistently failed in our stability tests after digging four other pits along the way with stable results (<a href="https://youtu.be/zCKlHstJTqc"><strong>video</strong></a&gt;). The new snow is generally bonding well, but in areas with a wet snow interface (<a href="https://www.youtube.com/watch?v=smo7R2A_6ZU&amp;list=PLXu5151nmAvQDzKmH…’s Bacon Rind video</strong></a>) or a weak, faceted interface, it is not. Watch Alex’s <a href="https://www.youtube.com/watch?v=TAWRM8yRgUM&amp;list=PLXu5151nmAvQDzKmH…; from the Bridger Range and Doug’s videos from the <a href="https://www.youtube.com/watch?v=U1b5LjWLTac&amp;list=PLXu5151nmAvQDzKmH… Range</strong></a> and <a href="https://www.youtube.com/watch?v=VQd7lPN6zTQ&amp;list=PLXu5151nmAvQDzKmH… City</strong></a> to see how it is playing out regionally.</p>

<p>Today, recent and ongoing snowfall with increasing wind make human-triggered slides possible. The danger is rated MODERATE.</p>

<p>If you get out, please send us your observations no matter how brief. You can submit them via our <a href="https://www.mtavalanche.com/node/add/snow_observation"><strong>website<…;, email (<a href="mailto:mtavalanche@gmail.com"><strong>mtavalanche@gmail.com</strong></a…;), phone (406-587-6984), or Instagram (#gnfacobs).</p>