20-21

<p>In the last 48 hours the mountains around Bozeman and Big Sky got 3”, Taylor Fork 4” and 8” outside West Yellowstone. Yesterday’s gale-force wind scoured ridgetops and loaded slopes at all elevations and aspects. Snow was redistributed with no predictable pattern. The snowpack is weak and the recent snowfall and wind-loading has made it unstable. Again yesterday, facets at the ground were breaking on low-angled terrain with whumpfs and cracks (<a href="https://www.mtavalanche.com/images/21/cracking-s-gallatin"><strong><u>S. Gallatin</u></strong></a>, <a href="https://www.mtavalanche.com/node/23770"><strong><u>N. Madison</u></strong></a>). On steeper slopes a large avalanche was seen on the east side of Lionhead Ridge (<a href="https://www.mtavalanche.com/images/21/lionhead-ridge-avalanche"><strong…;), which is on the heels of a dozen avalanches my partner and I noted on Tuesday (<a href="https://youtu.be/Feyz2_4aNmU"><strong><u>video</u></strong></a&gt;).&nbsp; Furthermore, the Bridger Bowl Ski Patrol saw 2 fresh slides on the west side of the Bridger Range in Bostwick and Truman Gulch yesterday (<a href="https://www.mtavalanche.com/node/23771"><strong><u>details</u></strong>…;).</p>

<p>Avoid avalanche terrain today. Evidence continues to show that new snow, even a few inches, has a nasty habit of avalanching. Yesterday’s wind gave the mountains a villainous beating. New drifts are packed densely and will crack and avalanche. Triggering avalanches below or adjacent to a steep slope is possible, just as the skiers in Flanders Creek found on Saturday (if you haven’t seen the <a href="https://youtu.be/Tp5A5YRd43E"><strong><u>video</u></strong></a&gt;, you need to). Dave explains a rationale for sticking to low-angeled powder in his <a href="https://youtu.be/XzPIY1Q1cKo"><strong><u>video</u></strong></a&gt; at Bacon Rind. For today, the avalanche danger is rated CONSIDERABLE on all slopes since triggering slides is likely.&nbsp;&nbsp;&nbsp;</p>

<p>Yesterday’s snowfall buried a layer of <a href="https://avalanche.org/avalanche-encyclopedia/surface-hoar/"><strong><u>… hoar</u></strong></a> (large feathers of snow) that is a notorious weak layer. We will be digging and searching for this layer as we get more snow in the coming weeks, and you should too.&nbsp;</p>

<p>The mountains around Cooke City got 10” yesterday and 3” the day before (1.2” <a href="https://www.nrcs.usda.gov/wps/portal/nrcs/detail/null/?cid=nrcseprd1314… water equivalent</u></a>). Our concerns involve instabilities in the top 3’ of the snowpack:</p>

<ol>
<li>Recent wind drifts,</li>
<li>A weak layer of surface hoar that just got buried,</li>
<li>A layer of weak, faceted snow 2-3’ deep has been triggered on some slopes.&nbsp;</li>
</ol>

<p>The snowpack has gotten more complex and requires digging and testing to determine its stability. Given the new snow, strong wind and buried weak layers, slopes will be reactive to triggering. Stay out of avalanche terrain and be vigilant since a new weak layer of surface hoar was buried. It will take time to get a sense of its distribution, but for now we assume it is everywhere. For today the avalanche danger is rated CONSIDERABLE on all slopes.&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>