GNFAC Avalanche Forecast for Sun Mar 22, 2020
<p>Today the snowpack is stable on most slopes and avalanches are unlikely. Travel in avalanche terrain always comes with risk. Many people are traveling in more isolated corners of the backcountry which increases the chance one or two will find an unstable slope.</p>
<p>On Friday skiers in the Absarokas (outside the advisory area) unintentionally triggered a cornice which broke a large avalanche deep in the snowpack (<a href="https://www.mtavalanche.com/node/22491"><strong>photos and details</strong></a>), and a separate group triggered an avalanche that broke over three feet deep on weak sugary snow on the ground. Nobody was caught (<a href="https://www.mtavalanche.com/node/22486"><strong>photos and details</strong></a>). Avalanches on weak layers near the ground are unlikely, but carry big consequences. Recent activity reminds us to consider this instability before riding in avalanche terrain.</p>
<p>Dave was in the Taylor Fork on Friday and backed off a plan to ski steep terrain after he dug and found a poor snowpack structure (<a href="https://www.youtube.com/watch?v=PLgEkwzjb88&list=PLXu5151nmAvSbcbVf…;). His Instagram photos are not as cool as he hoped, but at least he went skiing and came home safe. Probe and dig to look for weak sugary snow at the base of the snowpack before riding steep slopes. Also keep an eye out for surface hoar buried about 8” deep (<a href="https://www.mtavalanche.com/images/20/surface-hoar-near-buck-ridge"><st…;). Stay far back from the edge along ridgelines and minimize time on slopes with large cornices above.</p>
<p>Yesterday a skier near Big Sky triggered a small wind slab on a high elevation northerly slope (<strong><a href="https://www.mtavalanche.com/node/22498">photo and details</a></strong>). He was in less consequential terrain and was not caught. Slides like this appear small, but carry large consequences where they can push you over cliffs or into terrain traps. Today the avalanche danger is rated LOW, but avalanches are not impossible. Continue to practice safe backcountry travel protocols and be diligent with snowpack and terrain assessment.</p>
<p>We will end daily avalanche forecasts on Sunday, April 5th and continue with general bulletins every Monday and Friday through April. Over the next couple weeks we will take down our weather stations and receive little to no observations from guides or ski patrol. With more people in the backcountry and ski areas closed, we need help gathering field data. If you get out, please send us your observations no matter how brief. You can fill out an <a href="https://mtavalanche.us17.list-manage.com/track/click?u=6653a830e4819c9e…; target="_blank">observation form</a>, email us (<a href="mailto:mtavalanche@gmail.com" target="_blank">mtavalanche@gmail.com</a>), leave a VM at 406-587-6984, or Instagram (#gnfacobs).</p>
Social Distancing in the Backcountry
These days we essentially have to treat other people like avalanche terrain during high danger, and keep our distance. These are challenging times and we hope all can enjoy the mountains to ease the stress.
Skier triggered wind slab on Wilson Peak
From IG post with #gnfacobs: "I triggered a small windslab, mid slope on the north face of Wilson. It was a a pretty stubborn slab that broke above me. Cross loaded from lookers right. 6-8” deep." Photo: B Gill
From IG post with #gnfacobs: "I triggered a small windslab, mid slope on the north face of Wilson. It was a a pretty stubborn slab that broke above me. Cross loaded from lookers right. 6-8” deep." Photo: B Gill
From IG post with #gnfacobs: "I triggered a small windslab, mid slope on the north face of Wilson. It was a a pretty stubborn slab that broke above me. Cross loaded from lookers right. 6-8” deep." Photo: B Gill
GNFAC Avalanche Forecast for Sat Mar 21, 2020
<p>There are two primary avalanche concerns today: one that you’re likely to encounter but is fairly manageable and one that is unlikely but very dangerous.</p>
<p>The snow surface will become wet and unstable this afternoon on sunny slopes. Wet slides will generally be confined to the surface snow, but at low elevations could involve the whole, shallow snowpack. Luckily, the conditions for wet avalanches are easily to identify and avoid. If you’re sinking deeper than your ankles in wet slush, it’s time to get off steep slopes. Plan ahead to avoid steep slopes at low elevation that’ll be sopping wet as you head back to the trailhead in the afternoon.</p>
<p>The other main concern is avalanches breaking at the ground. These slides are unlikely – until yesterday, it had been several weeks since our last report of a deep slide. However, yesterday, two different groups of skiers in the Absaroka Range (outside of our advisory area) triggered large avalanches breaking near the ground (<strong><a href="https://www.mtavalanche.com/node/22486">photos and details</a></strong>, <strong><a href="https://www.mtavalanche.com/node/22491">photos and details</a></strong>). One slide was triggered by a large cornice fall and the other by the third skier on the slope. Skiers north of Beehive Peak also sent in pictures of a deep slide that appears to have been triggered by a natural cornice fall earlier this week (<strong><a href="https://www.mtavalanche.com/node/22487">photos and details</a></strong>). Yesterday, Dave backed off a slope in the Taylor Fork after getting an unstable snowpack test result on weak snow near the ground (<strong><a href="https://www.youtube.com/watch?v=PLgEkwzjb88&list=PLXu5151nmAvSbcbVf…;). It was a high elevation, shady slope where the weak layers that formed months ago still haven’t gained much strength and the snowpack is shallow enough you could still impact them. It’ll take finding the wrong spot on a thin slope or a cornice fall to trigger one, but these slides are a good reminder to not forget the possibility of a deeper avalanche.</p>
<p>Surface hoar buried earlier this week is a less widespread concern, but worth looking out for (<a href="https://www.mtavalanche.com/images/20/surface-hoar-near-buck-ridge"><st…;). Skiers near Cooke City yesterday found it buried about a foot deep on Abiathar Peak.</p>
<p>The avalanche danger is LOW this morning. The danger will rise to MODERATE on sunny slopes as the day heats up.</p>
<p>We will end daily avalanche forecasts on Sunday, April 5th and continue with general avalanche bulletins every Monday and Friday through the month. In the coming weeks will begin taking down weather stations during our field visits. With more people in the backcountry and ski areas closed, we need help gathering field data.</p>
<p>If you get out, please send us your observations no matter how brief. You can fill out an observation form, email us (mtavalanche@gmail.com), leave a VM at 406-587-6984, or Instagram (#gnfacobs).</p>
Upcoming Avalanche Education and Events
The GNFAC and Friends avalanche education programs have been cancelled due to the coronavirus. Thank you to all our amazing instructors for a great year of education!
Our education calendar lists awareness lectures and field courses offered by other providers: Events and Education Calendar.
Skier triggered cornice and deep slab on Emigrant Peak
Skiers on Emigrant Peak (outside advisory area) triggered a large cornice from the ridgeline. It broke 75' away from them and triggered a large avalanche when it hit the slope below. The avalanche broke 3-9' deep on weak snow near the ground. The avalanche was 150' wide and ran ~1000'. No one was caught.
A look at the footstep that triggered a large cornice on Emigrant Peak (outside of advisory area). The cornice fall triggered a large avalanche. 3/20/2020.
Photo: Z. Miller