20-21

<p>The snowpack has weak snow near the ground (sugary facets/depth hoar), but is mostly stable. <em>Weak</em> and s<em>table</em> are contradictory terms but describe two different things. The snow structure is poor since it’s foundation is crumbly snow. It can not hold much weight, especially weight that is applied quickly such as a big snowstorm, and is considered weak. Yet it is mostly stable because it is in a state of rest. The snowpack is relaxed, feeling good and not being tasked to hold up a big load of new snow.&nbsp;</p>

<p>Weak layers near the ground are scary because avalanches will be deep, but triggering them is unlikely on most slopes. The exceptions are isolated areas with a thin snowpack where a person could trigger a slide and have it propagate under adjacent, deeper snow. Dave and I were in Tepee Basin yesterday and found weak snow 5-feet under the surface and got it to break in our stability test (<a href="https://youtu.be/8Q4gTjESoq0"><strong><u>video</u></strong></a&gt;), a cautionary message that a skier or rider could trigger a slide on the wrong slope. In order to deal with the uncertainty of these conditions we adhere to strict travel protocols just in case we err and trigger a slide. Ian’s<strong> </strong><a href="https://youtu.be/gPWSDAr-K1Q"><strong><u>video</u></strong></a&gt; from Tuesday in the northern Bridger Range lays this travel advice on us clearly: only expose one person at a time, watch each other from a safe spot, carry rescue gear and take a quick look at the snow layering before diving onto steep terrain.&nbsp;</p>

<p>For today, the avalanche danger is rated LOW on all slopes.&nbsp;</p>

<p>A caveat: Wet, loose snow avalanches could occur on steep slopes if the temperatures are warmer than predicted. Roller balls and pinwheels of snow are signs of instability at the surface and a warning that steep slopes should be avoided.</p>

<p>The mountains around Cooke City got an inch of snow last night with no wind. This is not enough snow to adversely affect the good snow stability, especially since slopes lack a widespread weak layer. Snowfall on Monday and Tuesday (6-10”) may have been blown into drifts and skiers on Tuesday saw small avalanches involving only new snow (<a href="https://mtavalanche.com/images/21/storm-slab-cooke-city"><strong><u>pho…;). These isolated instabilities are reminders to carry rescue gear, travel one at a time, watch each other and take a moment to assess the snowpack before committing to steep terrain. Overall the mountains have safe avalanche conditions 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>The mountains near West Yellowstone, Big Sky, and Bozeman received 4-8” of snow equal to 0.4-0.7” of <a href="https://www.nrcs.usda.gov/wps/portal/nrcs/detail/or/snow/?cid=nrcs142p2… water equivalent</a>-SWE in the last 48-hours. In his <a href="https://www.youtube.com/watch?v=gPWSDAr-K1Q"><strong>video</strong></a&…; from the Northern Bridgers, Ian provides a good discussion of how to responsibly explore more adventurous terrain in a year defined by deeply buried persistent weak layers. He suggests taking “baby steps” rather than going all-in on big objectives in complex or exposed terrain, evaluating the snowpack to minimize surprises, and rigorously following safe travel protocols by exposing <em>only one person at a time</em> to potential avalanche hazards. As he said, “It may be unlikely, but if you trigger a slide, it could be catastrophic.” Recently, groups in Hyalite and near Hebgen Lake followed this travel model, found areas of unstable snow, and pulled the plug on skiing steep terrain. This is precisely how it should work in periods of low danger. Search for isolated instabilities and adjust your plans if you find them.</p>

<p>The last human-triggered avalanches we know of occurred ten days ago in the Madison Range (<a href="https://www.mtavalanche.com/weather/wx-avalanche-log"><strong>avalanche… log</strong></a>). Without significant new loading, deep-slab avalanches are unlikely, but the weak facets near the ground and the fundamental nature of the snowpack haven’t changed (<a href="https://www.youtube.com/watch?v=H8RLSPzsCtc"><strong>video</strong></a&…; from the Throne, <a href="https://www.youtube.com/watch?v=jHcGBFkyLbk&amp;list=PLXu5151nmAvQDzKmH…; from Maid of the Mist).</p>

<p>Today, follow Ian’s travel advice and pay attention to instabilities within the new snow. Storm snow avalanches will be relatively small but they can be hazardous in the context of steeper or more technical terrain. The avalanche danger is LOW.</p>

<p>The mountains around Cooke City received 6-10” of new snow equal to 0.6” of SWE. Yesterday, skiers observed several small storm slab avalanches (<a href="https://mtavalanche.com/images/21/storm-slab-cooke-city"><strong>photo<…;). Slides like this are dangerous in the context of steep and technical terrain if they tumble us into trees or off cliffs. Stay heads up for areas where yesterday’s wind may have drifted snow and enhanced potential avalanches’ size. Minimize time spent under behemoth cornices that overhang slopes this time of year. A cornice collapse on a small slope west of Cooke City is a good indicator of what a fall would be like where they are larger (<a href="https://mtavalanche.com/images/21/cornice-drop-west-cooke"><strong>phot…;). Watch for areas of isolated instability like the wind-loaded slope a rider triggered east of Cooke City on Friday (<a href="https://mtavalanche.com/node/24583"><strong>photos and details</strong></a><strong>: EVENT DATE CORRECTED</strong>), carry rescue gear, and expose only one person at a time to avalanche terrain. The avalanche danger is LOW.</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>