24-25

<p>While dangerous avalanche conditions persist in the mountains around Island Park, West Yellowstone, Big Sky and Cooke City, we are allowing the Avalanche Watch to expire as less snow has fallen than anticipated. Intensifying snow on Sunday may still lead to an Avalanche Warning before the storm is over.</p>

<p>New and wind-drifted snow is overloading widespread, persistent weak layers buried 1-2 feet deep (<a href="https://www.youtube.com/watch?v=01zVyy8U8D8&amp;t=23s">West Yellowstone</a>,&nbsp;<a href="https://youtu.be/4xSA_C9cPuc?feature=shared"><span>Island Park</span></a>, <a href="https://www.youtube.com/watch?v=FKh0OZ-BnUs"><span>Bacon Rind</span></a>, <a href="https://www.youtube.com/watch?v=yuTTHqltBiw"><span>Bridgers videos</span></a>). Human-triggered <strong>persistent slab avalanches</strong> are likely on slopes steeper than 30 degrees. Backcountry travelers could trigger slides that break remotely on nearby slopes above, below or to the side, necessitating cautious route-finding. While wind-loaded areas are the most unstable, all steep slopes are suspect.</p>

<p>Yesterday, riders near West Yellowstone reported collapses and shooting cracks, and skiers south of Cooke City avoided steep slopes after getting very unstable test results. The day before, cracks shooting up to 100 feet in the southern Madison Range were eye-opening (<strong><a href="https://www.mtavalanche.com/snow-observations-list"><span>observation page</span></a></strong>). When red flags indicating instability, including avalanches, collapsing and shooting cracks, are present, snowpits and tests are not required, but a cautious travel plan that largely avoids avalanche terrain and runout zones is.</p>

<p>Enjoy the new snow on slopes under 30 degrees without steep terrain immediately uphill. The avalanche danger is CONSIDERABLE.</p>

<p>Weak layers buried 1-2 feet deep in the Bridger and Northern Gallatin Ranges make triggering a <strong>persistent slab avalanche</strong> possible. However, with less recent snow than other portions of the forecast area, the likelihood is lower. Yesterday, a small, natural <strong>wind slab</strong> on Saddle Peak was a reminder of a secondary avalanche concern (<strong><a href="https://www.mtavalanche.com/node/32649"><span>details</span></a></stron…;). Mark and I found a stronger-than-average snowpack in the Divide Peak Basin yesterday, but variability across a mountain range and known weak layers resist blanket statements, especially this early in the season (<strong><a href="https://www.mtavalanche.com/node/32650"><span>media and observation</span></a></strong>).</p>

<p>Avoid wind-loaded slopes where persistent slab and wind slab avalanches are most likely. Evaluate the snowpack for instability before considering steep terrain in wind-sheltered areas. Move to lower-angle terrain in the presence of recent avalanche activity, cracking, collapsing and unstable test scores.</p>

<p>The avalanche danger is MODERATE.</p>