22-23

<p><span><span><span><span><span><span>Over the last week around a foot of snow fell in the mountains near West Yellowstone and Cooke City. There is a weak layer of surface hoar beneath the new snow on most slopes (</span></span></span></span></span></span><a href="https://youtu.be/1mFc__nNwIk"><span><span><span><strong><span><u><span>…;, </span></span></span></span></span></span><a href="https://youtu.be/ECi646U0Rtg"><span><span><span><strong><span><u><span>… Fork</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>, </span></span></span></span></span></span><a href="https://youtu.be/iBS_5itbX_U"><span><span><span><strong><span><u><span>… City</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span> videos). We haven’t seen avalanches on this layer yet, but there have been whumpfs and poor test scores (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/27622"><span><span><span><strong><span…;). The reason we’ve been focusing on this layer so much, even without avalanches breaking on it yet, is that surface hoar is notorious for catching even experienced professionals off guard. Avalanches on it can be triggered from the flats and break much wider or further above you than you might expect. Dig down to test this layer before riding steep slopes.&nbsp;</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>The weak layers at the ground are our other major concern. Triggering a slide on these layers would take finding just the wrong weak spot, but the resulting slide could be huge. Identify likely shallow areas (the most likely triggering spots) and steer clear of them. Be on high alert if the track of your snowmobile is digging to the ground or you’re punching through when you step out of your skis, as this means you’ve found a thin, weak area. For today, large avalanches are possible and the danger is rated MODERATE.</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>There has been less new snow around Bozeman and Big Sky, but our concerns are similar. Without much of a fresh load, avalanches are getting more difficult to trigger with each passing day. The weak snow near the ground is still weak and thin layers of faceted snow mid-pack could also break (</span></span></span></span></span></span><a href="https://www.youtube.com/watch?v=D38XfiTnFwU"><span><span><span><strong>… video</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>). Last weekend, there were a number of natural and human triggered avalanches (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/avalanche-activity"><span><span><span><stro… activity list</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>). Similar slides could be triggered today. Dig and test for instability, but also just keep your objectives appropriate for a mid-winter snowpack with several known weak layers that have a recent history of avalanching.</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>Yesterday, in Hyalite skiers triggered a thin wind slab that was only a couple inches deep, but propagated 40 ft wide (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/27633"><span><span><span><strong><span…;). Stay alert because even a thin avalanche in a little bit of wind drifted snow could be dangerous in high consequence terrain. The avalanche danger is rated MODERATE today.&nbsp;</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>Please share avalanche, snowpack or weather observations via our</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/add/snow_obs"><span><span><span><span>…; </span></span></span></span></span></span><span><span><span><strong><span><u><span><span>website</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>, email (</span></span></span></span></span></span><span><span><span><strong><span><span>mtavalanche@gmail.com</span></span></strong></span></span></span><span><span><span><span><span><span>), phone (406-587-6984), or Instagram (#gnfacobs).&nbsp;</span></span></span></span></span></span><span><span><span><span><span><span>&nbsp;</span></span></span></span></span></span></p>

<p>In Island Park, there is a weak layer of surface hoar beneath the new snow on most slopes. Avalanches on it can be triggered from the flats and break much wider or further above you than you might expect. Dig down to test this layer before riding steep slopes. Triggering a slide on weak layers near the ground would take finding just the wrong weak spot, but the resulting slide could be huge.</p>

<p><span><span><span><span><span><span>Since Sunday morning 10-14” fell in the southern mountains including Cooke City. A few avalanches were reported, mostly human triggered and small. These broke either underneath recent wind-loads or at the new/old snow interface. A list can be found on our </span></span></span></span></span></span><a href="https://www.mtavalanche.com/avalanche-activity"><span><span><span><stro… Activity</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span> page.&nbsp;</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>There are 2 weak layers we are concerned about: a recently buried layer of feathery surface hoar crystals one foot deep, and a thick layer of larger facets near the ground. The layer at the ground is less reactive but could be triggered from shallow spots resulting in a large avalanche. The buried surface hoar is assumed to be everywhere. On some slopes, like around Hebgen Lake (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/27622"><span><span><span><strong><span…;), it is reactive with whumpfs and poor test scores while on other slopes it is not. Dave explains in these 2 videos (</span></span></span></span></span></span><a href="https://youtu.be/1mFc__nNwIk"><span><span><span><strong><span><u><span>…;, </span></span></span></span></span></span><a href="https://youtu.be/ECi646U0Rtg"><span><span><span><strong><span><u><span>… Fork</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>) that we need to look for these layers. Ian and I found surface hoar in Cooke City on Tuesday (</span></span></span></span></span></span><a href="https://youtu.be/7BS-6onztVI"><span><span><span><strong><span><u><span>… 1</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>) and spent yesterday morning riding around and tracking its distribution (</span></span></span></span></span></span><a href="https://youtu.be/iBS_5itbX_U"><span><span><span><strong><span><u><span>… 2</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>). We found it on different aspects and elevations in all 5 of our pits. It may become reactive with more snow or already be primed to slide on slopes with wind-drifting.</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>We are making a big deal about buried surface hoar because it’s a big deal. It is notorious for spotty distribution and for catching even seasoned professionals off guard. For today, avalanches are possible and the danger is rated MODERATE.</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>Our </span></span></span></span></span></span><a href="https://www.mtavalanche.com/snow-observations-list"><span><span><span><… visits and public observations</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span> in the mountains around Bozeman and Big Sky showed instability last weekend. A natural avalanche </span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/27587"><span><span><span><strong><span… Fairy Lake</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>,&nbsp; </span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/27587"><span><span><span><strong><span…; </span></span></strong></span></span></span><span><span><span><span><span><span>and </span></span></span></span></span></span><a href="https://www.mtavalanche.com/images/23/snowboarder-caught-small-slide"><…; avalanches at Buck Ridge, a skier triggered slide in the </span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/27582"><span><span><span><strong><span… Sky sidecountry</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>, and a large avalanche on </span></span></span></span></span></span><a href="http://www.mtavalanche.com/node/27536"><span><span><span><strong><span>… Peak</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span> last Friday illustrate the lingering issue of unstable snow. Without snowfall, avalanches are getting more difficult to trigger with each passing day. The weak snow near the ground is still weak and thin layers of faceted snow mid-pack could also break (</span></span></span></span></span></span><a href="https://youtu.be/D38XfiTnFwU"><span><span><span><strong><span><u><span>…’s video</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>). Mother Nature is not giving us daily clues regarding instability, so we need to be diligent in our assessment and travel smart. Digging and testing is always a good idea because sometimes we find the unexpected. It’s also the time when traveling one at a time and carrying rescue gear can save us if we make a mistake. For today, triggering avalanches is possible and the danger is rated MODERATE.&nbsp;</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>Please share avalanche, snowpack or weather observations via our</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/add/snow_obs"><span><span><span><span>…; </span></span></span></span></span></span><span><span><span><strong><span><u><span><span>website</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>, email (</span></span></span></span></span></span><span><span><span><strong><span><span>mtavalanche@gmail.com</span></span></strong></span></span></span><span><span><span><span><span><span>), phone (406-587-6984), or Instagram (#gnfacobs).&nbsp;</span></span></span></span></span></span><span><span><span><span><span><span>&nbsp;</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>There are 2 weak layers we are concerned about: a recently buried layer of feathery surface hoar crystals one foot deep, and a thick layer of larger facets near the ground. The layer at the ground is less reactive but could be triggered from shallow spots resulting in a large avalanche. The buried surface hoar is assumed to be everywhere and may become reactive with more snow or already be primed to slide on slopes with wind-drifting. </span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/27607"><span><span><span><strong><span… snowmobiler triggered slide</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span> near Mt. Jefferson is evidence of the current instability. </span></span></span></span></span></span></p>