21-22

<p>It snowed more than 4 feet (4.3” <a href="https://www.nrcs.usda.gov/wps/portal/nrcs/detail/null/?cid=nrcseprd1314… water equivalent</u></a>) in the last 8 days in the southern mountains including Cooke City (<a href="https://www.mtavalanche.com/weather/wx-avalanche-log"><strong><u>weather log</u></strong></a>). Yesterday’s 4” of new snow coupled with strong wind and more snow today is making dangerous avalanche conditions on wind-loaded slopes. On Monday two snowmobilers were killed on one of these slopes and these are not any safer today (<a href="https://www.mtavalanche.com/node/25278"><strong><u>incident</u></strong…;). Other avalanches in Cooke City (<a href="http://www.mtavalanche.com/images/21/natural-slide-henderson-wind-loade…;, <a href="http://www.mtavalanche.com/images/21/human-triggered-avalanche-mount-ab…;) and “one monster whumph” in Bacon Rind are signs that instability continues. A whumpf is the sound of a weak layer breaking and propagating under you. It is an avalanche on flat terrain and a sign of instability. Avoid avalanche terrain that has been wind-loaded. Slopes without a wind load still harbor a weak layer of faceted, sugary snow that is propagating in stability tests. Dig and investigate slopes before blindly committing to avalanche terrain. For today, the danger is rated CONSIDERABLE on wind-loaded slopes and MODERATE on all others.</p>

<p>Dave gets a gold star for “walking the talk”. We preach hunting for instability even when things seem safe. Yesterday, Dave and his partner toured into the northern Bridger Range with an expectation of finding stable snow. It did not turn out that way. He dug his first pit low on a slope and surprisingly found a weak layer breaking clean. He dug 5 more pits and got breaks on some more. A thin layer of weak, faceted crystals (called near-surface facets) was in the middle of the 2-3 foot deep snowpack. He did not get into avalanche terrain. Instead, he made a <a href="https://youtu.be/kXE-CWnV_NY"><strong><u>video</u></strong></a&gt; explaining why. Other skiers found this layer too. Given the discovery of this new weak layer and potential for triggering avalanches on it we recommend digging and avoiding avalanche terrain if you find it. Additionally, strong west wind is building shallow drifts that could be triggered. For today the avalanche danger is rated MODERATE on all slopes.</p>

<p>Strong west wind is blowing in the northern Madison and northern Gallatin Ranges. Two inches of new snow and a few more today will be blown into drifts. These will be found near the ridgelines and in gullies and I anticipate a person could trigger a few wind slabs. On slopes without a wind load the stability is good. Although there is weak, faceted snow near the ground it is currently not a problem. In the last week we’ve either visited or had reports from Mt Ellis, Mt Wheeler, Lick Creek, Mt Blackmore, Beehive Basin (<a href="https://youtu.be/ePMCJs3qAs0"><strong><u>video</u></strong></a&gt;) and Buck Ridge (<a href="https://youtu.be/cf-qqv2Ssjw"><strong><u>video</u></strong></a&gt;) where generally stable conditions exist.</p>

<p>For today, it remains possible to trigger slides on wind-loaded slopes which have a MODERATE danger. On all other slopes avalanches are unlikely and the danger is rated LOW.&nbsp;</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><u>websi…;, email (<a href="mailto:mtavalanche@gmail.com"><strong><u>mtavalanche@gmail.com</u></str…;), phone (406-587-6984), or Instagram (#gnfacobs).</p>

<p>In the last 7 days Cooke City and the southern ranges, including West Yellowstone, have gotten 4 feet of snow and wind making unstable conditions on wind-loaded slopes. The avalanche on Scotch Bonnet outside Cooke City could have occurred in any of the southern ranges since the snow structure and instability are similar. Snow was blown and packed into dense drifts that are poorly supported by weak, sugary facets 12-18” off the ground. Ian and I found this combination at the crown of the avalanche (<a href="http://www.mtavalanche.com/images/21/ian-crown-avalanche-killed-2-snowm…;). In the last 48-hours skiers saw a slide on Henderson Bench (<a href="http://www.mtavalanche.com/images/21/natural-slide-henderson-wind-loade…;) and riders triggered two small avalanches on Mt Abundance (<a href="http://www.mtavalanche.com/images/21/human-triggered-avalanche-mount-ab…;).&nbsp;&nbsp;</p>

<p>Our recent field investigations in Lionhead (<a href="https://www.youtube.com/watch?v=qumV6n73pTs&amp;list=PLXu5151nmAvT1nrM2…;) and Taylor Fork (<a href="https://www.youtube.com/watch?v=rdVk9B7UbtQ&amp;list=PLXu5151nmAvT1nrM2…;) illustrate the likelihood of&nbsp; triggering slides on wind-loaded terrain. It is best to avoid these slopes. They will be found near ridgelines, above treeline and in gullies. The wind is still loading slopes and it is likely a skier or rider could trigger a large avalanche. For today, the danger is rated CONSIDERABLE on wind-loaded slopes and MODERATE on all others.</p>

<p>The mountains around Bozeman and Big Sky have gotten snow over the last 5 days: 12+” in the Bridgers, a foot in Hyalite and 6-8” in Big Sky. Skiing and riding has improved and folks are sending us observations. The snowpack is generally stable, but like most things in life there’s an exception: wind-loaded slopes could avalanche. These will not be deep or widespread, but triggering them is a possibility. Evidence of wind-loading are cornices, smooth pillows of dense snow and shooting cracks, a bullseye sign of instability.&nbsp;</p>

<p>With a trend toward stability signs of danger may not be prominent (avalanche activity, whumphing, etc).&nbsp; Weak, faceted snow near the ground is widespread and should be looked at and tested before diving into avalanche terrain. We must hunt for instability because it’s much better to be the hunter than the hunted. We do not like surprises which is why we dig. Our field videos&nbsp; last week should be a starting point for your stability assessment: <a href="https://www.youtube.com/watch?v=_MhpDHnH8So"><strong><u>Saddle Peak</u></strong></a>, <a href="https://youtu.be/cf-qqv2Ssjw"><strong><u>Buck Ridge</u></strong></a> and <a href="https://youtu.be/ePMCJs3qAs0"><strong><u>Beehive Basin</u></strong></a>.&nbsp; For today, it remains possible to trigger slides on wind-loaded slopes which have a MODERATE danger. On all other slopes avalanches are unlikely and the danger is rated LOW.&nbsp;</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><u>websi…;, email (<a href="mailto:mtavalanche@gmail.com"><strong><u>mtavalanche@gmail.com</u></str…;), phone (406-587-6984), or Instagram (#gnfacobs).</p>