A natural avalanche on the Fin near Cooke City was observed on 01/12 that happened a couple of days ago on 01/10 during a recent storm. Photo: B. Fredlund
A natural avalanche on the Fin near Cooke City was observed on 01/12 that happened a couple of days ago on 01/10 during a recent storm. Photo: B. Fredlund
From email Jan 12: "Natural avalanche on the Fin of Mt. Republic observed this morning.
The timing of it looks to be about 36-48hrs ago.
Looks like it might have started at the new/old snow interface, and then stepped down into deeper layers mid face.
Quite an impressive avalanche!"
Collapsing, shooting cracks (30ft+), and whumpfing noted while breaking trail on the W aspect of Henderson. Frequency increased with elevation. Natural avalanches noted on E faces of Miller, Republic, and Henderson. Also natural avalanches on SW face of Scotch Bonnet.
Broke loose a slide just below the radio tower standing above the crown. Broke about 30 cm down on a layer of weak snow.
Also saw very unstable snow pack at the top of the main gully below the radio tower, large cracking and settling. Snow propagated across but came to a stop before a slide began. Large chunks of snow and debris broken off from the cornice to above main gully.
From email 1/12: "From this morning. Looks to be 1_1.5' deep. Maybe a few different ones based on what I can tell."
Email later on 1/12: "Thinking about it more, that avalanche might have happened last night. (with .4" of SWE at Fisher Creek since 4pm yesterday, and increased wind speeds). Almost a full reset of the surface snow up on west Mt. Henderson this afternoon."
Recent natural avalanche on the Fin in Cooke City. This likely happened during or near the end of the last storm on 01/10. Photo: B. Zavora
From email: "From this morning. Looks to be 1_1.5' deep. Maybe a few different ones based on what I can tell."
<p><span><span><span><span><span><span>Human triggered avalanches are likely today. A very weak snowpack has been loaded by snow and wind over the last week and is avalanching, including being triggered from a distance.</span></span></span></span></span></span></p>
<p><span><span><span><span><span><span>Yesterday, in the Taylor Fork, I triggered an avalanche that broke 30 ft away on the first steep slope I got near, while walking on a flat ridgeline (</span></span></span></span></span></span><a href="https://www.youtube.com/watch?v=aTnE5gzG1sc"><span><span><span><strong>…;). Throughout the day we got cracks shooting out 50-100 ft on every slope with even a hint of wind effect and triggered another small slide that broke 2.5 ft deep on a short slope. Doug and his partner triggered a 1,000’ wide avalanche on Tuesday at Lionhead (</span></span></span></span></span></span><a href="https://youtu.be/QNkJeGFSPYs"><span><span><span><strong><span><u><span>…;, </span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/29836"><span><span><span><strong><span… and observation</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>). These are clear demonstrations of how weak and touchy the snowpack is right now. These slides were breaking on surface hoar beneath the new snow, but slides could also break on the weak faceted layers throughout the lower snowpack.</span></span></span></span></span></span></p>
<p><span><span><span><span><span><span>We’ve known for weeks and months that the snowpack was remarkably weak and it was going to avalanche once we built a cohesive slab on top (</span></span></span></span></span></span><a href="https://youtu.be/K_t6Fi6wUC4"><span><span><span><strong><span><u><span>… snow recap video</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>). We’ve now built that slab. Don’t push your luck today. Avalanches can break wide and be triggered from afar. Avoid traveling on or beneath any steep slope. </span></span></span></span></span></span></p>
<p><span><span><span><span><span><span>The avalanche danger is CONSIDERABLE.</span></span></span></span></span></span></p>
<p><span><span><span><span><span><span>The northern Gallatin Range has received less new snow than elsewhere and despite lots of new snow yesterday in the Bridger Range it was very low density and noncohesive (</span></span></span></span></span></span><a href="https://www.youtube.com/watch?v=GJxMtiIQGbs"><span><span><span><strong>… Range video</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>). There are still a variety of avalanche concerns to watch out for. Dangerous sluffs can be triggered in areas with more new snow or gouging into the unconsolidated lower snowpack on very steep slopes (</span></span></span></span></span></span><a href="https://www.youtube.com/watch?v=Y0LROtnc7Us"><span><span><span><strong>… Ridge video</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>). Also watch out for cohesive slabs of wind drifted snow, because they are almost assuredly sitting over weak layers. Seeing shooting cracks, collapses, or recent avalanches are all bullseye evidence of unstable conditions and should lead to a quick retreat from steep slopes. Do a quick snowpack test to double check that you’re not missing something. Give yourself a big safety margin with these dangerously frigid temperatures.</span></span></span></span></span></span></p>
<p><span><span><span><span><span><span>Human triggered avalanches are possible and the avalanche danger is MODERATE.</span></span></span></span></span></span></p>
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