17-18

<p>Snow stability is variable in the mountains around Cooke City. Some slopes have a deep and stable snowpack, while others have buried weak layers capable of producing avalanches. A layer of surface hoar 1-2’ deep has produced unstable results in stability tests and may be the culprit of recently triggered avalanches (<a href="https://www.mtavalanche.com/images/18/remote-triggered-soft-slab"><stro…;, <a href="https://www.mtavalanche.com/images/18/remote-triggered-soft-slab-0"><st…;). This layer has sporadic distribution making careful snowpack evaluation essential.</p>

<p>Facets buried deeper in the pack also remain a concern. A large natural avalanche on Woody Ridge south of town is a good reminder of what’s still possible (<a href="https://www.mtavalanche.com/images/18/natural-avalanche-woody-ridge"><s…;). Today, the likelihood of a triggering a slide increases on wind loaded slopes. Watch for and avoid wind loaded areas and assess non-wind loaded slopes carefully before traveling in avalanche terrain.</p>

<p>Read a recent blog post on the complexities of the snowpack around Cooke City: <a href="https://www.mtavalanche.com/blog/additional-thoughts-regarding-my-uncer…;

<p>For today, the avalanche danger is rated <strong>CONSIDERABLE </strong>on wind loaded slopes and <strong>MODERATE</strong> on non-wind loaded slopes.</p>

<p>The snowpack is getting stronger in the southern ranges (<a href="https://youtu.be/-5OhvArl2P0"><strong>video</strong></a&gt;), but there are isolated instabilities too look for. On Tuesday, Doug and I skied into Bacon Rind in the southern Madison Range and had a layer of surface hoar propagate in our stability test (<a href="https://youtu.be/thn9hnFUi4Y"><strong>video</strong></a><strong&gt;, </strong><a href="https://www.mtavalanche.com/images/18/ectp-12-bacon-rind"><strong>photo…;). Alex also got unstable results on this layer near West Yellowstone earlier in the week (<a href="https://youtu.be/gKvrr5JHODA"><strong>video</strong></a&gt;). Buried surface is not producing widespread instability, but should be looked for and assessed before riding steeper slopes. In addition to buried surface hoar, wind slabs could also produce human triggered slides. Fresh wind slabs most likely exist on slopes leeward to west-northwest winds. Avoid slopes below cornices or any areas that have large pillows of wind drifted snow.</p>

<p>Today, buried surface hoar and wind slabs make human triggered avalanches possible and the avalanche danger is rated <strong>MODERATE</strong>.</p>

<p>The primary avalanche problem in the mountains around Bozeman and Big Sky is wind slabs. On Tuesday, 3-5” of low density snow fell across the northern areas. This snow was transported onto leeward slopes by moderate to strong winds out of the west-northwest. Yesterday, my partner and I skied around Mt Blackmore in Hyalite and observed large cornices and wind loading along the ridgelines (<strong><a href="https://www.youtube.com/watch?v=-Kh4wvvQ3Wk">video</a></strong&gt;). While many wind-loaded slopes will be stubborn to trigger, some could avalanche from the weight of a skier or rider. Search for wind-loading in gullies, on roll-overs, and of course, under ridgelines (<a href="https://www.mtavalanche.com/images/18/wind-blowing-snow-bridgers"><stro…;). Outside of wind loaded slopes, the snowpack is mostly stable.</p>

<p>For today, the avalanche danger is rated <strong>MODERATE</strong> on all wind-loaded slopes and <strong>LOW</strong> elsewhere.</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>In the last few days Cooke City has gotten wind, snow and avalanches. Yesterday, winds blew 60-70+ mph at all elevations and a large natural avalanche on Woody Ridge broke at the ground, estimated to be over 8’ deep on a heavily wind-loaded slope (<strong><a href="https://www.mtavalanche.com/images/18/natural-avalanche-woody-ridge">ph…;). Two cornice triggered avalanches on Town Hill also released yesterday. Additionally, there were two smaller slides were remotely triggered over the weekend (<a href="https://www.mtavalanche.com/images/18/remote-triggered-soft-slab"><stro…;, <a href="https://www.mtavalanche.com/images/18/remote-triggered-soft-slab-0"><st…;). A layer of surface hoar buried 1-2’ deep, has been unreactive in tests, but it cannot be ruled out as a culprit in past and future avalanches. Given the new snow, very strong winds, recent avalanches, and buried surface hoar, there are only a couple ways to safely proceed: 1. Avoid all wind-loaded slopes, and 2. Dig and test the upper few feet of the snowpack to find instability. For today, the avalanche danger is rated <strong>CONSIDERABLE</strong> since human triggered avalanches are likely.</p>

<p>Yesterday, the southern mountains had strong winds and a couple inches of new snow. Our field visits outside West Yellowstone (<strong><a href="https://youtu.be/gKvrr5JHODA">video</a></strong&gt;) and Cabin Creek (<a href="https://youtu.be/-5OhvArl2P0"><strong>video</strong></a&gt;) indicate the snowpack is strengthening, but there are isolated instabilities too look for, such as facets near the ground and feathery crystals of surface hoar buried 1-2 feet under the surface. Eric and I skied into Bacon Rind yesterday and had the surface hoar propagate in our stability test, a sign of instability (<strong><a href="https://youtu.be/thn9hnFUi4Y">video</a&gt;, <a href="https://www.mtavalanche.com/images/18/ectp-12-bacon-rind">photo</a></st…;). The layer is found on many slopes, but is only unstable on a few. This was one of those few. As snowpack strengthens, signs of instability disappear so we have to dig and test if we want to play in avalanche terrain. For today, the avalanche danger is rated<strong> MODERATE</strong> on all slopes.</p>

<p>Wind blew and snow fell in the northern mountains: 5” in the Bridger Range and in Hyalite, and 2” around Big Sky. The snow fell with warm temperatures which will help the 12-18” thick wind slabs bond to the old surface. While many wind-loaded slopes will be stubborn to trigger, some could avalanche from the weight of a skier or rider. Since the wind blew fierce at all elevations, search for wind-loading in gullies, on roll-overs, and of course, under ridgelines (<strong><a href="https://www.mtavalanche.com/images/18/wind-blowing-snow-bridgers">photo…;). For today, the avalanche danger is rated <strong>MODERATE</strong> on all wind-loaded slopes and <strong>LOW</strong> elsewhere.</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>