24-25

<p>The mountains around West Yellowstone and Cooke City, including the Southern Madison and Southern Gallatin Ranges, have gone a week without significant snowfall but only three days without a significant avalanche (<a href="https://www.mtavalanche.com/node/34421"><span>Lionhead photos and observation</span></a>). Today, the primary concern is<strong> persistent slab avalanches</strong> failing on weak layers buried 2-3 feet deep and breaking up to 200 feet wide. Instability on these layers is the most pronounced in the Lionhead area and Southern Gallatin and Southern Madison Ranges, with mid-elevation, non-wind-loaded terrain being the most likely trigger points. In the last two weeks, backcountry riders triggered many avalanches with several burials and close calls (<a href="https://www.mtavalanche.com/node/34413"><span>Thursday in Cabin Creek</span></a>, <a href="https://www.mtavalanche.com/node/34368"><span>last Monday in Cooke</span></a>, last weekend in <a href="https://www.mtavalanche.com/node/34341"><span>Tepee Basin 1</span></a>, <a href="https://www.mtavalanche.com/node/34301"><span>Tepee Basin 2</span></a>, <a href="https://www.mtavalanche.com/node/34367"><span>Cooke City</span></a>, <a href="https://www.mtavalanche.com/node/34327"><span>Taylor Fork</span></a>, and <a href="https://www.youtube.com/watch?v=tAiSHSEDJhY"><span>Lionhead two Wednesdays ago</span></a>).</p>

<p>The odds of triggering an avalanche decrease each day without new snow, but my trust is hard-earned regarding these weak layers buried like active mines on some slopes and inactive ones on many others.</p>

<p><strong>Travel Advice:</strong> If you plan to play on slopes steeper than 30 degrees, dig and test for instability. To reduce the consequences of an avalanche, choose slopes with fewer terrain traps, such as trees, cliffs, and gullies. Follow safe travel practices and be ready for an avalanche rescue by carrying and training with beacons, shovels and probes.</p>

<p><span>The avalanche danger is rated MODERATE.<span>&nbsp; </span></span></p>

<p>Several inches of new snow in the mountains around Bozeman and 1-2” near Big Sky do not significantly change the avalanche danger. Snow showers are forecast to end soon without much more accumulation, and slides today will generally be shallow, isolated to <strong>loose snow avalanches </strong>or sluffs in steeper terrain and small <strong>wind slab avalanches</strong> where the snow is drifted. Recognize potential instability by noting shooting cracks and deeper drifts.<span>&nbsp; </span></p>

<p>As I discussed in my <a href="https://youtube.com/shorts/dmVA7qCtspA?feature=share"><span>video</span…; from the northern Bridger Range yesterday, after backing off our targeted run, many things need to come together to consider steeper and committing backcountry objectives more safely. While most avalanche terrain remains generally stable, a few inches of new snow rewrites the equation in very steep and extreme terrain where small avalanches can have big consequences.</p>

<p>The avalanche danger is LOW.<span>&nbsp; </span></p>

<p>Avalanches are unlikely in the Centennial Mountains in Island Park. Without recent snow, conditions are generally safe. As I discussed in my <a href="https://youtube.com/shorts/dmVA7qCtspA?feature=share"><span>video</span…; from the Bridger Range yesterday, many things need to line up to consider steep and committing backcountry objectives, including avalanche conditions, snow surface conditions, visibility and partners with the right gear and training. For now, the avalanche conditions component is lined up well. A snowstorm favoring the mountains in Island Park will begin on Thursday, improving riding conditions and increasing the avalanche danger.</p>

<p>Follow standard safe travel protocols and be cautious traveling above or below cornices that can break unexpectedly far back from their edge.</p>

<p><span>The avalanche danger is LOW.<span>&nbsp;</span></span></p>

<p><span><span><span><span><span><span>Today’s primary avalanche problem is human-triggered </span></span></span></span></span></span><span><span><span><strong><span><span>persistent slab avalanches</span></span></strong></span></span></span><span><span><span><span><span><span> breaking on weak layers that formed in late January. Over the previous 12 days we received reports of multiple persistent slab avalanches, breaking 2-3 feet deep and 50-200 feet wide. The most recent, that we know of, were triggered by snowmobilers on Friday at Lionhead (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/34421"><span><span><span><span><span><… and observation</span></span></u></span></span></span></span></span></a><span><span><span><span><span><span>). One slide broke 5 feet deep on a heavily wind-loaded slope (</span></span></span></span></span></span><a href="https://www.youtube.com/watch?v=TWCNOrvNvLk&amp;embeds_referring_euri=h…;). Many recent avalanches were close calls with riders narrowly avoiding being caught and some partially buried and dug out by partners (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/34413"><span><span><span><span><span><… in Cabin Creek</span></span></u></span></span></span></span></span></a><span><span><span><span><span><span>, </span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/34368"><span><span><span><span><span><… Monday in Cooke</span></span></u></span></span></span></span></span></a><span><span><span><span><span><span>, last weekend in </span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/34341"><span><span><span><span><span><… Basin 1</span></span></u></span></span></span></span></span></a><span><span><span><span><span><span>, </span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/34301"><span><span><span><span><span><… Basin 2</span></span></u></span></span></span></span></span></a><span><span><span><span><span><span>, </span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/34367"><span><span><span><span><span><… City</span></span></u></span></span></span></span></span></a><span><span><span><span><span><span>, </span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/34327"><span><span><span><span><span><… Fork</span></span></u></span></span></span></span></span></a><span><span><span><span><span><span>, and </span></span></span></span></span></span><a href="https://www.youtube.com/watch?v=tAiSHSEDJhY"><span><span><span><span><s… two Wednesdays ago</span></span></u></span></span></span></span></span></a><span><span><span><span><span><span>).&nbsp;</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>During our visits to Lionhead on Friday and the southern Madison Range on Saturday (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/34438"><span><span><span><span><span><…;) we dug down and found the weak layers creating a poor structure in our snowpits. Although the weak layers were stubborn and did not produce many unstable test results, the recent avalanche activity is evidence to be cautious of steep slopes.</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>The problem is tricky because unstable slopes are not widespread, and many (not all) recent slides have been on mid-elevation slopes, surrounded by trees and sheltered from the wind. These may be less typical places you would consider avalanches. Your best options are either avoid slopes steeper than 30 degrees, or before committing to steep slopes dig down 3-4 feet to check for buried weak layers, and choose slopes with minimal consequences such as gullies, trees or cliffs (</span></span></span></span></span></span><a href="https://youtu.be/W_BeKTJQbUc?feature=shared"><span><span><span><span><s… from Saturday</span></span></u></span></span></span></span></span></a><span><span><span><span><span><span>).&nbsp;</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>The avalanche danger is MODERATE near West Yellowstone and Cooke City.</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>Near Bozeman, Big Sky and Island Park avalanches are unlikely. Cooler temperatures and cloudy skies will end the threat of wet snow avalanches that were the main concern over the weekend. Additionally, we have not seen deeper persistent slab avalanches like we have in other areas, and drifts that formed last week should be glued on.&nbsp;</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>A couple things to keep in mind are large cornices along ridgelines and small drifts that might form with new snow and light to moderate wind later today.&nbsp;</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>On Saturday skiers in Hyalite noted cornices peeling off the ridgeline and a cornice fall that triggered a wind slab avalanche (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/34440"><span><span><span><span><span><…;). Cooler temperatures should prevent cornices from breaking naturally today, but some may be teetering on edge after the recent above freezing temperatures. Stay far back from the edge of cornices if you travel along ridgelines.</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>If snow starts early or piles up quickly some small fresh drifts might form late this afternoon. These should be generally harmless, but a small wind slab avalanche could knock you over. Be careful of fresh drifts on steep slopes where a small slide could carry you a long distance or push you over cliffs or into trees.&nbsp;</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>The avalanche danger is LOW near Bozeman, Big Sky and Island Park.</span></span></span></span></span></span></p>