21-22

<p>Snowfall between Friday night to Sunday morning dropped 12-14” of snow in the mountains around Cooke City with up to 0.9” of <a href="https://www.nrcs.usda.gov/wps/portal/nrcs/detail/null/?cid=nrcseprd1314… water equivalent</a> (SWE). Human-triggered avalanches are likely on slopes where 15-20 mph winds are transporting this snow into unstable slabs. Alex saw evidence of recent natural avalanches on Miller Mountain and explained in his <a href="https://www.youtube.com/watch?v=5Y9gdD8IOwM"><strong>video</strong></a&…; yesterday that the new and drifted snow is sitting on top of a weak layer of facets creating dangerous avalanche conditions. Other skiers in the Cooke City area observed recent <a href="https://mtavalanche.com/node/25763"><strong>natural avalanches on Woody Ridge</strong></a> and just outside the advisory area in <a href="https://mtavalanche.com/node/25760"><strong>Yellowstone National Park</strong></a><strong>. </strong>All of these avalanches are failing on weak layers of snow now buried 18-24” deep (<a href="https://www.mtavalanche.com/images/22/buried-surface-hoar-layer-ynp-nea…;). Avoid wind-loaded slopes where avalanches are likely, and the danger is CONSIDERABLE. Avalanches are possible on non-wind-loaded slopes and the danger is MODERATE. Carefully evaluate the snowpack and avoid areas with terrain traps that would amplify the consequences of an avalanche.</p>

<p>Two nights ago, 4” of snow fell in the Northern Gallatin Range equal to 0.3” SWE adding to the 10” earlier in the week. The wind increased late yesterday afternoon and will continue to transport recent snow into unstable drifts where avalanches large enough to injure or bury climbers, skiers and riders are possible. On Saturday, a group in the Flanders drainage witnessed snow pouring off an ice climb that “probably would have slammed a climber off the route” (<a href="https://www.mtavalanche.com/node/25744"><strong>details</strong></a&gt;). Today, carefully assess the snowpack paying special attention for signs of wind-loading such as blowing snow and shooting cracks in the snowpack. Avoid terrain where features like trees, cliffs and rocks act as terrain traps and smaller avalanches would be dangerous. Human-triggered avalanches are possible today, and danger is MODERATE.</p>

<p>Sadly, a rider triggered a fatal avalanche on Ski Hill in the Lionhead area yesterday. The shallow slide broke across the slope on a steep rollover and the rider was swept into trees and partially buried. Unfortunately, life-saving efforts on-scene were unsuccessful (<a href="https://mtavalanche.com/node/25766"><strong>limited details and photos</strong></a>). Nearby, a different group triggered a small, relatively harmless avalanche that failed 12” deep on buried weak layers (<a href="https://mtavalanche.com/node/25767"><strong>details and photos</strong></a>). In the Southern Gallatin Range a group of skiers got a “whumph” on a small, isolated slope at low elevations, another indicator of weaker snow. Large avalanches in the West Yellowstone area and near Big Sky and in the Bridger Range are unlikely with the above activity being the tragic&nbsp;exception to overall stability. Additionally, these events&nbsp;signify more trouble to come when the wind blows or snow returns.</p>

<p>There is not much soft snow left for transport in the Northern Madison and Bridger Ranges, but windy conditions today may create small drifts adding to those formed this weekend where you could find isolated instabilities especially where they are combined with buried weak-layers 6-18” under the snow surface (<a href="https://www.mtavalanche.com/images/22/northern-bridger-unstable-pit-res…;). Assess the snowpack for localized instabilities prior to entering steep terrain and evaluate the terrain for features that amplify the consequences of small avalanches. 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>