20-21

<p>In the mountains surrounding Bozeman, last night’s 4-6” of new snow (measuring .3-.5” of <a href="https://www.nrcs.usda.gov/wps/portal/nrcs/detail/or/snow/?cid=nrcs142p2… water equivalent</u></a>-SWE) and gusty west to northwest wind will keep the potential for triggering avalanches alive and well. The new snow will be blown into drifts which will likely crack and avalanche on steep slopes. Additionally, in the last 36 hours almost 1 inch of SWE has fallen, which is a decent amount of weight to put on a snowpack that has poor structure and is seen as untrustworthy. Ian was in the Bridger Range on Tuesday and found a thin, weak, faceted snowpack (<a href="https://youtu.be/js1BXvovZ4I"><strong><u>Throne video</u></strong></a>). Skiers on Mt. Blackmore yesterday found the new snow bonding well to the old, but the sugary facets at the ground are still concerning. Stay clear of avalanche terrain; the snowpack is under new stress from the new snow and wind-loading. Triggering avalanches is likely. For today the avalanche danger is rated CONSIDERABLE on all slopes.</p>

<p>Last night a few inches fell around Big Sky while most of the snowfall arrived yesterday morning near West Yellowstone and Cooke City. In general, the weight of new snow (.5-.7” <a href="https://www.nrcs.usda.gov/wps/portal/nrcs/detail/or/snow/?cid=nrcs142p2…; in 36 hours) and wind-loading makes it possible to trigger slides today, but it is not a sure thing. That makes navigation a bit tricky. Many avalanches last weekend (<a href="https://www.mtavalanche.com/avalanche-activity"><strong><u>full list here</u></strong></a>, <a href="https://youtu.be/CI0HFvtLrf4"><strong><u>Lionhead video of major avalanche cycle</u></strong></a>) and a snowmobile triggered slide on Monday at Lionhead (<a href="https://www.mtavalanche.com/node/24049"><strong><u>details</u></strong>…;) broke on weak layers near the ground (sugary facets) or midpack (2’ from the surface). Noteworthy slides include a very large skier-triggered avalanche on Ernie Miller Ridge near Bacon Rind on Saturday (<a href="https://youtu.be/dVWv0RA9WMM"><strong><u>video</u></strong></a&gt;, <a href="https://www.mtavalanche.com/node/23991"><strong><u>details</u></strong>…;) and another <a href="https://www.mtavalanche.com/node/24021"><strong><u>large avalanche on the Fin</u></strong></a> outside Cooke City. Avalanches will be more difficult to trigger after last week’s wallop, but two things should be considered: first, the faceted (sugary) weak layers that the avalanches broke on are still&nbsp;</p>

<p>there, and second, the new snow and wind-loading has added weight that will keep these layers from becoming dormant. Avoid avalanche terrain entirely if you see signs of instability such as cracking, collapsing or fresh avalanches. For today the avalanche 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><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 Bridger, Gallatin and Madison Ranges and Lionhead area, 4-6” fell in three hours measuring .5” of <a href="https://www.nrcs.usda.gov/wps/portal/nrcs/detail/or/snow/?cid=nrcs142p2… water equivalent</u></a>-SWE. The snowpack was loaded quickly and more snow today will continue raising the avalanche potential. Ian toured into the Throne of the northern Bridger Range yesterday and found conditions to be dismal: thin and weak. In his <a href="https://youtu.be/js1BXvovZ4I"><strong><u>video</u></strong></a&gt; he describes a poor snow structure which will be especially untrustworthy with today’s new snow.&nbsp;</p>

<p>Since Friday there have been <a href="https://www.mtavalanche.com/avalanche-activity"><strong><u>14 reports of avalanche activity</u></strong></a><strong>,</strong> some noting multiple slides. These were breaking on weak layers buried in the snowpack: near the ground and also midpack. I investigated a major avalanche cycle in Lionhead on Monday (<a href="https://youtu.be/CI0HFvtLrf4"><strong><u>video</u></strong></a&gt;, <a href="https://www.mtavalanche.com/node/24045"><strong><u>details</u></strong>…;), the same day a sledder triggered an avalanche in the area. Also on Monday, Dave looked at a monster avalanche near Bacon Rind that was skier triggered from far away (<a href="https://youtu.be/dVWv0RA9WMM"><strong><u>video</u></strong></a&gt;, <a href="https://www.mtavalanche.com/node/23991"><strong><u>details</u></strong>…;).&nbsp; In&nbsp; Taylor Fork (<a href="https://www.mtavalanche.com/node/24014"><strong><u>video and details</u></strong></a>), <a href="https://www.mtavalanche.com/node/24051"><strong><u>Speciman Creek</u></strong></a> and <a href="https://www.mtavalanche.com/node/24056"><strong><u>Fawn Pass</u></strong></a> more avalanches and red flags (whumpfing and cracking) were seen.</p>

<p>Snowfall will continue and the wind is blowing strong enough to create drifts which add even more weight to an unstable snowpack.&nbsp; Stay clear of avalanche terrain. It will be easy to trigger slides during the storm. Traveling near or under avalanche terrain is a dangerous proposition and the danger is rated CONSIDERABLE on all slopes.</p>

<p>The mountains around Cooke City received 3” of snow with southwest wind gusting into the 30s. Weak layers of faceted crystals 1-2’ deep and another buried 3’ deep avalanched on many slopes after last week’s snowfall. A <a href="https://www.mtavalanche.com/node/24021"><strong><u>large avalanche on the Fin</u></strong></a> broke deeply on Saturday and over the weekend skiers noted <a href="https://www.mtavalanche.com/node/23997"><strong><u>many other avalanches</u></strong></a> on different aspects and elevations. If snowfall continues the danger will rise. With limited visibility, wind and snow, it is a good idea to avoid steep slopes. At the first sign of instability, such as cracking , collapsing or fresh avalanches, hightail it away from avalanche terrain. For today the avalanche danger is rated MODERATE, but could rise to CONSIDERABLE if 6+” fall during the day.&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>