21-22

<p>A few inches of new snow is not enough weight to adversely affect the stability of the snowpack. Wind at the ridgeline may create thin pockets of drifted snow, but these won’t be deep or widespread. Yesterday, Ian and his partner toured up Flanders drainage in Hyalite. They dug a snowpit on a slope adjacent to where they were planning to ski and got unstable test results, which is not what they were expecting (<a href="https://youtu.be/-ha6ugs0Wgs"><strong><u>video</u></strong></a&gt;). He said, “I’d much rather get surprised in my snowpit than surprised by an avalanche.” This is why we dig, even when avalanches are unlikely. Knowing what’s under our feet is critical information.&nbsp;</p>

<p>South of Big Sky to West Yellowstone and Cooke City, the snowpack is stable but we just buried a new weak layer, a future problem. Feathery crystals of surface hoar that formed during clear nights (<a href="http://www.mtavalanche.com/images/22/west-yellowstone-surface-hoar"><st…;) are now 1-3” under the snow surface. Alex is in Cooke City and confirmed they are now buried and preserved (<a href="http://www.mtavalanche.com/images/22/buried-surface-hoar-near-cooke-cit…;, <a href="https://youtu.be/FOJv3cTQ8rs"><strong><u>video</u></strong></a&gt;). Yesterday, I found them under the surface in Lionhead near West Yellowstone (<a href="https://youtu.be/g7Pl9-raU7g"><strong><u>video</u></strong></a&gt;). Their distribution is widespread at most elevations and aspects in the southern mountains. This specific weak layer is resistant to strengthening and can remain a problem for a month or more. I expect avalanches on this layer once we get more snow, but not today.</p>

<p>The basics of avalanche safety never get old, they keep us trained and focused. Carry rescue gear, practice with it, only expose one person at a time on a slope and dig and test before committing to avalanche terrain. Today the avalanche danger is rated LOW on all slopes in the forecast area since avalanches are unlikely.&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>The snowpack across the advisory area is generally stable and the expected snow won’t be enough weight to change this. However, don’t mistake today’s overall stability to mean an absence of weak layers. Riders and skiers have spotted a feathery layer of weak surface hoar growing from West Yellowstone to Cooke City. When it gets buried today, this will be our new layer of concern until proven otherwise (<a href="https://mtavalanche.com/images/22/surface-hoar-near-cooke-city"><strong… photo</strong></a><strong>, </strong><a href="https://mtavalanche.com/images/22/west-yellowstone-surface-hoar"><stron… photo 1</strong></a><strong>, </strong><a href="https://mtavalanche.com/images/22/surface-hoar-formation-lionhead"><str…;). It will not be a significant hazard with the minimal snow arriving today, but it will be as it gets buried deeper. Help us map its extent by <a href="https://mtavalanche.com/node/add/snow_obs"><strong>letting us know</strong></a> if you see it on the surface or see shooting cracks and surprising reactivity in today’s inch or two of new snow.</p>

<p>Without significant new loading, Doug and Alex remind us to focus on the basics during times of low danger by testing the snowpack, assessing for isolated instabilities and employing safe travel practices (<a href="https://www.youtube.com/watch?v=bmstU9sCAmM"><strong>Doug in the Bridger Range</strong></a><strong>, </strong><a href="https://www.youtube.com/watch?v=8gxJKiQe_Jo"><strong>Alex in Cooke City</strong></a>). Groups in the Madison, Northern Gallatin and Bridger Ranges have reported <a href="https://www.youtube.com/watch?v=Gk8W8nlUMpw"><strong>snowpits</strong><… have&nbsp;failed and propagated in isolated areas, indicating a potentially unstable combination of a buried weak layer and an overlying slab of snow (<a href="https://mtavalanche.com/images/22/ernest-miller-ridge"><strong>photo</s…;). These groups (and all the ones who are reporting stable test results) are nailing it! They know that even though avalanches are generally unlikely, they need to test stability to make a slope-specific forecast before skiing or riding. If they identify areas of isolated instability, they go somewhere else. Keep it up.</p>

<p>Today, human-triggered avalanches are unlikely to break deeper than the 1-2” of new snow that falls during the day, and the danger is 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>website<…;, email (<a href="mailto:mtavalanche@gmail.com"><strong>mtavalanche@gmail.com</strong></a…;), phone (406-587-6984), or Instagram (#gnfacobs).</p>