Ski Cut Avalanche in Wyoming Bowl
A member of our party intentionally triggered a 30-40cm storm slab on a small convexity in treed terrain in Wyoming Creek.
A member of our party intentionally triggered a 30-40cm storm slab on a small convexity in treed terrain in Wyoming Creek.
Skier in Republic Creek observed a natural (wind/storm slab) avalanche on an east aspect at ~9200ft. Photo: R. Minton
Very deep snow past Round Lake today. New snow ranged from 2-4’ deep. My elbows and shouldered were touching the trenches of my sled track as I rode through Star Lake toward the wilderness boundary. New snow was very low density. No natural avalanches observed and ski cuts were non reactive on test slopes.
Traveled up Republic Creek, ascending to ridge separating Wyoming and Republic Creeks. Trailbreaking was arduous, ski pen ~ 60-80cm depending on travel under canopy or in more open terrain. Did not formally evaluate HST, suffice to say it was significant. HS 260cm at 9600ft. Skies obscured all day with varying snowfall rates, S1-3. Moderate W/SW winds and PLENTY of transport. Observed a D2 natural (wind/storm slab? Hard to say from my vantage) on E aspect at ~9200ft. A member of our party intentionally triggered a 30-40cm storm slab on a small convexity in treed terrain in Wyoming Creek. No other natural or skier triggered activity observed, though visibility limited our view to the more complex terrain further up Republic. Ended the day with a Woody Ridge lap and encountered no cracking/slabbing of new snow in this zone. Snowfall was intensifying as we left the drainage around 1700.
Observed a few old avalanches today, maybe from the 2/8 storm. Although well out of the advisory area, helpful for skiers in the Red Lodge Area.
1) Silver Falls Cr (Lake Fork), 9200', E, HS-N-R4-D1.5-O 45cm thick pencil hardness slab, HS 135. Pulled out into upper 20 degree terrain. 2-3 avalanches here, with one crown ~600' long.
2) Misery Bowl (Main Fork), 9400', ESE, HS-N-R2-D2.5-O A few avalanches here similar to above, with one significantly larger avalanche appearing to have failed on depth hoar where the bowl tips South. 2-4' crown, ran about 600' vertical.
Toured the ramp this morning. We found a lot of snow covering the skin track from yesterday. Little to no wind affect near the ridge, however we did find the occasional deep, slightly stiff drift on more northerly/easterly aspects. While skiing a se facing slope, we found cracking and some cohesion in the new snow. This was mostly on very steep and rocky terrain features. The most notable of these was about 20’ wide, the bottom part of the new slab only moved about 6” before stopping, while the upper foot of the slab ran the full face. Most steep chutes we skinned near had a debris pile at the bottom (running full path).
<p><span><span><span><span><span><span>A person can easily trigger avalanches that involve the recent snow. These will be largest and most likely where the snow has drifted into thicker slabs. On non-wind-loaded slopes large avalanches are possible, and more likely in areas with the most snow. </span></span></span></span></span></span></p>
<p><span><span><span><span><span><span>Since Friday the mountains near Bozeman and Big Sky received up to two feet of snow equal to 1.0-2.2” of snow water equivalent (SWE) with the highest amounts in the northern Bridgers. The last few days we received reports of </span></span></span></span></span></span><span><span><span><strong><span><span>wind slab avalanches </span></span></strong></span></span></span><span><span><span><span><span><span>(</span></span></span></span></span></span><a href="https://www.mtavalanche.com/images/25/intentionally-triggered-soft-slab…;) where the snow had been drifted, and </span></span></span></span></span></span><span><span><span><strong><span><span>storm slab avalanches</span></span></strong></span></span></span><span><span><span><span><span><span> on slopes that were less wind-loaded (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/34210"><span><span><span><strong><span…;, </span></span></span></span></span></span><a href="https://www.mtavalanche.com/images/25/snowmobile-triggered-avalanche-bu…;). </span></span></span></span></span></span><span><span><span><strong><span><span>Loose dry avalanches</span></span></strong></span></span></span><span><span><span><span><span><span> are also likely and will be largest where the most snow fell. </span></span></span></span></span></span></p>
<p><span><span><span><span><span><span>Check out Dave’s </span></span></span></span></span></span><a href="https://www.youtube.com/shorts/hf1nmcVcC_s"><span><span><span><strong><… from Beehive</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span> yesterday for current insight on these avalanche problems. Expect these problems to grow in size and likelihood as more snow falls today.</span></span></span></span></span></span></p>
<p><span><span><span><span><span><span>Plan to avoid wind-loaded slopes steeper than 30 degrees, and before crossing or riding other steep slopes carefully assess the stability of recent snow. Watch for cracking across the snow surface or recent avalanches as signs that the new snow is unstable. Consider smaller slopes that are sheltered from the wind and with minimal terrain traps like thick trees or cliffs, or avoid steep slopes altogether. The avalanche danger is CONSIDERABLE.</span></span></span></span></span></span></p>
<p><span><span><span><span><span><span>Near West Yellowstone, Island Park, and Cooke City received 1-1.5 feet of snow equal to 1.2-1.4” SWE since Friday. Similar to the northern parts of our forecast area, the primary concern is </span></span></span></span></span></span><span><span><span><strong><span><span>wind slab avalanches</span></span></strong></span></span></span><span><span><span><span><span><span> on slopes where the snow was drifted into thicker or stiffer slabs, and on non-wind-loaded slopes </span></span></span></span></span></span><span><span><span><strong><span><span>storm slab avalanches</span></span></strong></span></span></span><span><span><span><span><span><span> are possible. Over the weekend we received reports of these types of avalanches in Cooke City (</span></span></span></span></span></span><a href="https://mtavalanche.com/node/34189"><span><span><span><strong><span><u>… and observation 1</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>, </span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/34215"><span><span><span><strong><span… 2</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>). With the snow totals continuing to add up today, expect these types of avalanches to be larger and more widespread.</span></span></span></span></span></span></p>
<p><span><span><span><span><span><span>In these southern parts of our forecast area <strong>p</strong></span></span></span></span></span></span><span><span><span><strong><span><span>ersistent slab avalanches</span></span></strong></span></span></span><span><span><span><span><span><span> could break on weak layers buried 2-3 feet deep. On Thursday in Taylor Fork Dave and I saw four avalanches that broke 1-2 feet deep on layers of sugary facets and feathery surface hoar. Yesterday we received a report from Lionhead of a rider triggered wind slab avalanche that triggered a deeper persistent slab avalanche (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/34208"><span><span><span><strong><span…;). Avalanche activity on these layers hasn’t been widespread, but they should not be ignored (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/34156"><span><span><span><strong><span… photo</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>, </span></span></span></span></span></span><a href="https://www.mtavalanche.com/images/25/cornice-triggered-avalanche-miner… City photo</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>,</span></span></span></span></span></span><span><span><span><strong><span><span> </span></span></strong></span></span></span><a href="https://www.youtube.com/watch?v=wZ3k35z5Ej8&embeds_referring_euri=h… Fork video</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>). As the new snow adds up the chance of triggering a larger persistent slab avalanche is increasing.</span></span></span></span></span></span></p>
<p><span><span><span><span><span><span>Avoid steep wind-loaded slopes, and before committing to any steep slope carefully assess the stability of recent snow and potential for buried weak layers. Avalanche danger is CONSIDERABLE on wind-loaded slopes and MODERATE on all others.</span></span></span></span></span></span></p>
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Level one avalanche class dug multiple pits. ECTN x3 45-60cm down and one ECTP #16 on the same layer below recent storms 50cm down. Height of snow ranges from 155-200cm around Bradley meadows.