Snowpack and Avalanche Discussion
<p>Dangerous avalanche conditions exist in the southern portions of the advisory area where a slab of cohesive snow sits on top of a weak foundation of sugary facets. Snowfall throughout the day will make conditions more dangerous. Slopes with wind-drifted snow are most likely to avalanche, but all are suspect.</p>
<p>In the past week, evidence of the danger included human-triggered and natural avalanches, shooting cracks, and whumphing collapses. On Sunday near West Yellowstone, a splitboarder had a close call on Lionhead Ridge while I made a video outlining the instability (<a href="https://www.mtavalanche.com/node/29358"><strong><span>avalanche details</span></strong></a>, <a href="https://youtu.be/ChZK6ex_f7k"><strong><span>video</span></strong></a>). Sledders from nearby in Island Park sent observations of natural avalanches and shooting cracks in Black Canyon (<a href="https://www.mtavalanche.com/node/29376"><strong><span>details</span></s…;, <a href="https://www.mtavalanche.com/node/29377"><strong><span>details 2</span></strong></a>). On Monday, riders in the Taylor Fork observed several avalanches and triggered two slides from one hundred feet away (<a href="https://www.mtavalanche.com/node/29373"><strong><span>details and photo</span></strong></a>). In Cooke City, the weak foundation of faceted snow couldn’t support last weekend’s storm avalanching naturally on some slopes (<a href="https://www.mtavalanche.com/node/29381"><strong><span>details and photos 1</span></strong></a>, <a href="https://www.mtavalanche.com/node/29354"><strong><span>2</span></strong>…;). On Tuesday, Alex and Ian triggered loud whumphs that told them conditions remained unstable (<a href="https://youtu.be/tCIhNk8uJoM"><strong><span>video</span></strong></a>).</p>
<p>Do not let the thin snow cover fool you. There is enough snow to avalanche, bury and injure skiers, riders and climbers. Avoid slopes steeper than 30 degrees as human-triggered avalanches are likely. The danger is rated CONSIDERABLE.</p>
<p>Human-triggered avalanches large enough to bury or injure climbers, skiers or riders are possible in the northern portions of the advisory area. Today, new and wind-drifted snow will further prime slopes with a weak foundation for avalanches.<span> </span></p>
<p>Groups will swarm to the gullies of Hyalite Canyon for this weekend’s Bozeman Ice Fest. Consider the locations of parties uphill and downhill of your group. On Monday, a climber in the Dribbles area observed cracking across the slope (<a href="https://www.mtavalanche.com/node/29362"><strong><span>observation and photo</span></strong></a>). Gullies funnel small avalanches into concentrated blasts that can knock people off their feet in consequential terrain.</p>
<p>In Big Sky, Alex made a <a href="https://www.youtube.com/watch?v=khUlf_rurog"><strong><span>video</span>…; </strong>showing a weak snowpack last week. Big Sky Ski Patrol’s snow safety team notes that the area’s snowpack is still weakening. During avalanche mitigation work on wind-loaded slopes, they have triggered several hard slab avalanches (<a href="https://www.mtavalanche.com/images/23/ski-patrol-triggered-hardslab-big…;).</p>
<p>Before considering steeper terrain, assess the snowpack for instability. Watch for signs of recent avalanches, shooting cracks or collapsing, and dig a snowpit to test for less obvious instability. Remember the adage, “If you are on a slope with enough snow to ski or ride, there is enough snow to slide.” The avalanche danger is rated MODERATE.</p>
<p>Dangerous avalanche conditions exist in Island Park where a slab of cohesive snow sits on top of a weak foundation of sugary facets. Snowfall throughout the day will make conditions more dangerous. Slopes with wind-drifted snow are most likely to avalanche, but all are suspect. Avoid slopes steeper than 30 degrees, as human-triggered avalanches are likely.</p>
<p>The avalanche danger is CONSIDERABLE.</p>
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