20-21

<p>The last large slab avalanches that we know of in the mountains around Bozeman, Big Sky, and West Yellowstone occurred on the last day of February when two different groups triggered slides that broke on sugary depth hoar near the ground, taking out most of the year’s snowpack (<a href="https://mtavalanche.com/weather/wx-avalanche-log"><strong>weather and avalanche log</strong></a>). Since then, skiers and riders have observed small wet, loose snow avalanches on warm sunny days and relatively small wind slab avalanches in recently drifted snow. Yesterday, the Bridger Bowl Ski Patrol noted several natural wet snow avalanches coming out of steep east-facing terrain.</p>

<p>Wet snow avalanche activity is likely to be minimal today and wind slabs are stabilizing. Pay attention to wet, slushy snow deeper than a few inches as a sign of increasing danger this afternoon and to isolated areas where wind-drifted snow may still crack and slide. Small avalanches or cornice fall in technical terrain can be deadly, so stay vigilant with your assessments and safe travel protocols. Watch our recent <a href="https://www.youtube.com/playlist?list=PLXu5151nmAvQDzKmH5K3ZS8Gg3DzwsZ3… from the field</strong></a> to review these avalanche concerns.</p>

<p>We are not forgetting about the weak snow near the ground. It will return to the forefront of the conversation when melt-water penetrates deep into the snowpack or if significant spring snowstorms arrive, but for now, triggering an avalanche on this layer is unlikely. The avalanche danger is LOW.</p>

<p>It may not have snowed in Cooke City as forecast, but at least it got windy. For several hours last night 15-25 mph wind transported the remaining soft snow into drifts that could crack and avalanche today. Wind-slabs are likely to be small and on isolated terrain features but could cause significant problems in high consequence terrain. Recent cornice collapses near Abiathar and Mount Fox remind us to minimize time spent under these overhanging masses of snow (<a href="https://www.mtavalanche.com/node/24618"><strong>details</strong></a&gt;). Cooler temperatures and cloudy skies will limit warming today but keep wet, loose snow avalanches in mind if the sun pops out this afternoon. Generally safe avalanche conditions exist in Cooke City and the 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>

<p>Several isolated avalanche concerns remain in the mountains around Bozeman, Big Sky, and West Yellowstone. Small wind-slabs or drifts of snow can avalanche under the weight of a skier or rider. Yesterday, my partner and I saw these in the Northern Bridger Range, skiers noted them around Beehive Peak, and the Big Sky Ski Patrol triggered a slab that broke up to 18” deep during avalanche mitigation work. These avalanches are likely too small to bury someone but would be dangerous in extreme or technical terrain.</p>

<p>Water in the snowpack on slopes getting baked by the sun on warm days causes the snow to lose cohesion and slide downhill. If you sink deeper than mid-boot level into wet or slushy snow, move to a shadier aspect, a higher elevation, or call it a day. As I outlined in my <a href="https://youtu.be/HCjetG0dr0I"><strong>video</strong></a&gt; from the Northern Bridgers yesterday and Ian showed in <a href="https://www.youtube.com/watch?v=l5LfdUsd0Wk"><strong>Specimen creek</strong></a> last week, these are often aspect and elevation-driven events. Increasing cloud cover will minimize this danger today.</p>

<p>Finally, I had a stability test fail near the ground yesterday (<a href="https://mtavalanche.com/images/21/frazier-basin-profile-14-march"><stro… profile</strong></a>) and Doug had a massive slab fall in his lap in <a href="https://www.youtube.com/watch?v=8Q4gTjESoq0"><strong>Tepee Basin</strong></a> last week. Large avalanches failing on weak snow near the ground are unlikely but we cannot put these deeply buried weak layers out of our mind. Assess the snowpack and rigorously follow standard safe travel practices.</p>

<p>Human-triggered avalanches are unlikely and the danger is rated LOW.</p>

<p>Generally, safe avalanche conditions exist in Cooke City. If you are considering more adventurous terrain selection, keep a few things in mind. Small slab avalanches (<a href="https://www.mtavalanche.com/images/21/meridian-peak-avalanche"><strong>…;, <a href="https://www.mtavalanche.com/images/21/storm-slab-cooke-city"><strong>ph…;, <a href="https://www.youtube.com/watch?v=fRcnpNGTKCQ&amp;list=PLXu5151nmAvQDzKmH…;) and loose, wet snow avalanches if it warms up and stays sunny (<a href="https://www.mtavalanche.com/images/21/skier-triggered-loose-snow-slide-…;) can have severe consequences in steep terrain. Skiers and riders have encountered both of these isolated issues within the last week. Large cornices have collapsed recently. A group climbing a couloir on Abiathar was nearly hit by vehicle-sized chunks “raining down” on them (<a href="https://www.mtavalanche.com/node/24618"><strong>details</strong></a&gt;). Skiers also observed a recent cornice collapse on Mount Fox. Avalanches are unlikely today and the danger is rated 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>

<p>In the Bridger Range, strong east wind since yesterday afternoon drifted snow from earlier this week into fresh slabs. Watch out for these drifts in unusual locations due to the less common wind direction. Although not widespread, these wind slabs are possible to trigger and could be large enough to injure or bury a person. Large avalanches breaking on weak snow at the ground and small wet loose slides are unlikely, but should be kept in mind if you are riding&nbsp;steep slopes (more on those hazards below). Today, avalanche danger is MODERATE on wind-loaded slopes, and LOW on all other slopes.</p>

<p>In the mountains near Bozeman, Big Sky and West Yellowstone there is weak, sugary snow at the base of the snowpack (Doug’s video from <a href="https://www.youtube.com/watch?v=8Q4gTjESoq0"><strong>Teepee Basin</strong></a> last week shows this poor snowpack structure). It is unlikely to trigger an avalanche on this layer right now, but the result would have huge consequences. Carefully assess the snowpack and choose terrain to minimize the chances of encountering this deep slab hazard.</p>

<p>Another warm, sunny day creates a chance for small wet loose avalanches on slopes that receive direct sun. These slopes have a crust on the surface that formed from previous days of sunny, warm weather. Anticipate the possibility of wet loose avalanches later in the day, and avoid being underneath or on steep, sunny slopes if the crust has melted and the surface is wet. Wet slides will generally be small, but on isolated slopes where the snowpack is saturated, wet slides could gouge to the ground (<a href="https://www.youtube.com/watch?v=l5LfdUsd0Wk"><strong>Specimen creek video</strong></a>). Today, large avalanches are unlikely and the avalanche danger is LOW.</p>

<p>Yesterday near Abiathar Peak west of Cooke City, skiers were nearly hit by a large falling cornice while they were hiking up a steep chute (<strong><a href="https://www.mtavalanche.com/node/24618">details</a></strong&gt;). Most slopes are stable and avalanches are unlikely, but isolated hazards exist. These hazards may be small or unlikely, but are potentially deadly if you are in the wrong terrain. Snow that fell earlier this week created small slabs, and we saw loose snow avalanches that ran far on the firm crust underneath (<a href="https://www.mtavalanche.com/images/21/meridian-peak-avalanche"><strong>…;, <a href="https://www.mtavalanche.com/images/21/storm-slab-cooke-city"><strong>ph…;, <strong><a href="https://www.youtube.com/watch?v=fRcnpNGTKCQ&amp;list=PLXu5151nmAvQDzKmH…;). Today, be on the lookout for small wind slabs formed by recent moderate east wind, and loose snow slides and cornice falls as temperatures warm above freezing (<a href="https://www.mtavalanche.com/images/21/skier-triggered-loose-snow-slide-…;). Today,&nbsp;isolated hazards exist, and the avalanche danger is rated 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>