The Nose of Town Hill avalanched on Feb. 1 due to the strong SWerly winds and looked to be triggered by a cornice fall (estimated 2-3' crown, about 75-100' wide.
The Nose of Town Hill avalanched on Feb. 1 due to the strong SWerly winds and looked to be triggered by a cornice fall (estimated 2-3' crown, about 75-100' wide). Photo: B Fredlund
<p>On Monday morning, the Shower Falls Snotel Site reported 9” of new snow with 0.6” of <a href="https://www.nrcs.usda.gov/wps/portal/nrcs/detail/or/snow/?cid=nrcs142p2… water equivalent</a> (SWE). Yesterday, my partner and I toured into Mount Ellis and were unwilling to go into steep terrain because we feared we would trigger an avalanche. On our approach, the weak snowpack “whumphed” and cracked as we walked through areas where east winds had deposited snow in abnormal drifts (<a href="https://www.youtube.com/watch?v=HgnRrFSl3eU"><strong>video</strong></a&…;). Slopes with a thin and weak snowpack, such as Mt. Ellis, Flanders, and Wheeler, will be especially susceptible to avalanches breaking deep on buried weak layers (<strong><a href="https://www.youtube.com/watch?v=HLWnHKAslnM&list=PLXu5151nmAvSbcbVf…;). However, wind created problems all over the range. Climbers in the Main Fork of Hyalite triggered a small wind slab in high consequence terrain (<a href="https://www.mtavalanche.com/node/21846"><strong>avalanche activity</strong></a>) and skiers at Mount Blackmore reported fresh drifts of snow avalanching naturally on the north face and running 1000’ downslope.</p>
<p>The avalanche danger spiked during and immediately after the new snow fell on Sunday. Today, signs of instability like cracking and “whumphing” will be less likely, but the underlying problem is still present. Avoid steep wind loaded terrain and assess non-wind loaded slopes before entering avalanche terrain. The danger is CONSIDERABLE on wind loaded terrain, MODERATE everywhere else.</p>
<p>Strong winds and 7-14” of new snow over the weekend increased the avalanche danger. Wind loading is the common denominator in recent avalanche activity. In Cooke City, skiers reported seeing large deep slab avalanches and shallower slides where the wind had drifted snow (<a href="https://www.mtavalanche.com/images/20/cooke-city-wind-slab"><strong>pho… 1</strong></a>, <a href="https://www.mtavalanche.com/images/20/wind-slabs-woody-ridge"><strong>2…;, </strong><strong><a href="https://www.mtavalanche.com/images/20/cooke-city-deep-slab">3</a></stro…;). Skiers in Beehive Basin observed drifts in unusual areas from the east winds and stayed out of avalanche terrain after observing cracking and a recent natural avalanche above the Going Home Chute. Alex intentionally triggered a wind slab to demonstrate the problem as he describes in his <a href="https://www.youtube.com/watch?v=RKCwJUJ_-t4"><strong>video</strong></a>…; Avalanches within fresh drifts will be the most likely problem today, but large avalanches failing deep in the snowpack are still possible. While Doug might be tired of mentioning weak snow buried at the bottom of our snowpack (<a href="https://www.youtube.com/watch?v=a8pYH4O5sNo&list=PLXu5151nmAvSbcbVf…;), a 6-8’ deep avalanche that ran on Sunday on Naya Nuki demonstrates its continued relevance (<strong><a href="https://www.mtavalanche.com/node/21861">avalanche details</a></strong>). I was still seeing failures on this layer on recent field days in Cooke City (<a href="https://www.youtube.com/watch?v=DYbfFxcdGnI&list=PLXu5151nmAvSbcbVf…; and Ian was not ready to trust the layer of sugary snow near the ground even as it is showing signs of strengthening in Lionhead (<a href="https://www.youtube.com/watch?v=RNye2XVdYbY&list=PLXu5151nmAvSbcbVf…;
<p>Use extra caution on slopes with fresh drifts of snow and assess all slopes for stability before entering avalanche terrain. Today, human triggered avalanches are possible and the avalanche danger is rated MODERATE</p>
<p>If you get out, please send us your observations no matter how brief. You can fill out an <a href="https://www.mtavalanche.com/node/add/snow_observation"><strong>observat… form</strong></a>, email us (<a href="mailto:mtavalanche@gmail.com"><strong>mtavalanche@gmail.com</strong></a…;), leave a VM at 406-587-6984, or Instagram (#gnfacobs).</p>
Thanks to the 52 hikers and 9 Teams who rallied their supporters and fundraised for the event. "Strange Cattle of Map Brewing" raised the most money and Mountain Project hiked the most.
Saw this today while skiing. This crown is on a northeast aspect at about 8600 feet. Crown height 6-8 feet. It is mid path in the Great One. It seems to have naturally avalanched on Sunday during the storm, without a cornice trigger, after the wind event. All I can get here is that the slope was overloaded from storm snow, on top of a recently overgrown hard slab. Looks like it initiated higher up and pulled out much deeper below. Definitely a large hard slab avalanche. HS-N-R3-D3.5. Debris made it to the trees in the historic path. Otherwise, northeast aspects are loaded above 8500 feet, and I saw about 14 inches of new at 8000 feet. No loading during the day today.
Saw this today while skiing. This crown is on a northeast aspect at about 8600 feet. Crown height 6-8 feet. It is mid path in the Great One. It seems to have naturally avalanched on Sunday during the storm, without a cornice trigger, after the wind event. All I can get here is that the slope was overloaded from storm snow, on top of a recently overgrown hard slab. Looks like it initiated higher up and pulled out much deeper below. Definitely a large hard slab avalanche. HS-N-R3-D3.5. Debris made it to the trees in the historic path.
Climber caused icefall that triggered a small avalanche. Thankfully, the bed surface was ice just a few inches down and the belayer was just outside the path. Minor entrainment Photo: Anonymous
