Numerous slides observed on Saturday 3/18 on the flanks of Emigrant Peak during a tour up its east bowls. The largest ones seemed to be on SE aspects.
Numerous slides observed on Saturday 3/18 on the flanks of Emigrant Peak during a tour up its east bowls. The largest ones seemed to be on SE aspects.
Myself and two partners were skiing in the crazies 3/17-3/18. Dug 2 pits and got similar results, ectn15 18cm down and n28 30cm down with depths of 300-400cm and no deeper pwls on N/NE aspects at 8300ft and 9600ft. No recent avalanche activity other than a few small 6in storm/wind slabs on southern aspects. Snowpack was very right side up everywhere we toured and had skied 3 different NW to E faces. On 3/18 we headed to ski a NE facing couloir at 10000ft, skinned/booted the first ~300ft and found similar snow to everywhere else. About halfway up hit a rocky section with some depth hoar, I noted plate crystals up to 1cm wide at ground. Should’ve turned around there but thought maybe it was just a short rocky section. I had also just measured the slope angle at 52 degrees which gave me false confidence there would be no developed slab. Wallowed through weaker snow for another ~50ft then finally decided to turn around due to the difficult boot packing, hitting our 3pm turn around time, and the weak snow pack. As I booted to the middle of the line to find better snow the slab broke off 10-20ft above me wall to wall. I was the only one caught and was carried 500ft of vertical. Didn’t get buried and no lost gear so extremely lucky all around. The avalanche was estimated D2/R4 with a 18-30in crown and 30ft wide.
As we returned to Frazier Basin from below, we saw five natural avalanches on the southeast-facing wall of the basin. These had occurred while we were skiing the terrain below. They entrained only the 1 to 2 inches of snow that had fallen during the day. However, they were notable in that they ran 500 to 700 vertical feet. They were likely initiated by warming from the proximal cliff faces. They indicate that the new snow may not bond well to the old snow surface. A crust formed by the recent warm temperatures and sunny skies is the subsurface that snow is falling on. This will become a more significant concern as more snow falls this week.
As we returned to Frazier Basin from below, we saw five natural avalanches on the southeast-facing wall of the basin. They entrained only the 1 to 2 inches of snow that had fallen during the day. However, they were notable in that they ran 500 to 700 vertical feet. They indicate that the new snow may not bond well to the old snow surface. A crust formed by the recent warm temperatures and sunny skies is the subsurface that snow is falling on. This will become a more significant concern as more snow falls this week. Photo: GNFAC
We skied into Frazier Basin, and down into Ainger Lake area. We dug our first snow pit on a north-facing slope below Thing One and Thing Two. The Snowpack was deep, and the upper meter consisted of layers of wind slabs on top of wind slabs (Ectx). We dug again on a northeast-facing slope below Frazier basin. Similarly, we found a deep snowpack with no notable weak layers in the upper 4 feet. We dug a third pit on a southeast-facing slope as we skinned out. The snowpack was much thinner (140cm), and we found weak depth hoar buried 3 1/2 to 4 feet deep with an unstable test result (ectp21). The instability was related to the snow depth rather than the aspect. Given that there was a large natural avalanche a few basins to the south a week ago, we remain concerned about avalanches breaking deep in the snowpack.
As we returned to Frazier Basin from below, we immediately saw five natural avalanches on the southeast-facing wall of the basin. These had occurred while we were skiing the terrain below. They entrained only the 1 to 2 inches of snow that had fallen during the day. However, they were notable in that they ran 500 to 700 vertical feet. They were likely initiated by warming from the proximal cliff faces. They indicate that the new snow may not bond well to the old snow surface. A crust formed by the recent warm temperatures and sunny skies is the subsurface that snow is falling on. This will become a more significant concern as more snow falls this week.
Yesterday we toured up into Emigrant gulch. At around 2pm we observed a small point release on the East face of Emigrant, either a small cornice break or wet loose, that ran for about 200ft before stepping down to a deep slab that appeared to be about 3ft deep and 100ft across.
<p><span><span><span><span><span><span>The primary avalanche concern is the possibility for a person to trigger an avalanche that breaks on persistent weak layers buried at least 2-6 feet deep below hard slabs of snow. On Saturday near Cooke City a snowmobiler triggered a huge deep slab avalanche and was luckily unharmed (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/28695"><span><span><span><strong><span… and photos</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>). Yesterday, Dave and I rode in Taylor Fork and saw multiple deep slab avalanches that broke during heavy snowfall last week (</span></span></span></span></span></span><a href="https://www.youtube.com/watch?v=KJ0l4TlIh_I&list=PLXu5151nmAvTi1DBS…;, </span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/28725"><span><span><span><strong><span… and photos</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>). These avalanches broke on weak layers that were formed and buried in January. Over the past month, we have seen these large to very large avalanches break each time the mountains receive new snow (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/weather/wx-avalanche-log"><span><span><span… and avalanche log</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>), a sign we will be dealing with this instability as long as it keeps snowing. </span></span></span></span></span></span></p>
<p><span><span><span><span><span><span>We have seen the majority of deep slab avalanche activity near Cooke City and West Yellowstone (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/28673"><span><span><span><strong><span… observation</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.youtube.com/watch?v=ncKRJpdC-iE"><span><span><span><strong>…;), where more snow fell over the last month, but the possibility to trigger a large, deep avalanche also exists near Bozeman and Big Sky (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/28455"><span><span><span><strong><span… Peak slide</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/28642"><span><span><span><strong><span… Bridgers slide</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>). Before traveling on or underneath any steep slope, evaluate the snowpack for buried weak layers and wind-loading. Ski or ride small, simple slopes with minimal wind-loading, or slopes less than 30 degrees.</span></span></span></span></span></span></p>
<p><span><span><span><span><span><span>New snow today will be drifted into fresh slabs that could avalanche under the weight of a person, and add weight to the snowpack to increase the chances of triggering a deeper avalanche. Watch for cracking across the snow surface around your feet or skis as a sign fresh drifts are unstable and could avalanche on steeper slopes. Today’s snowfall will not rapidly increase the danger, but conditions will be dynamic. Choose objectives that are mellow, low consequence or low angle, or be ready to adjust your plan if you notice heavy snowfall or drifts growing quickly. </span></span></span></span></span></span></p>
<p><span><span><span><span><span><span>Heightened avalanche conditions exist and avalanche danger is MODERATE.</span></span></span></span></span></span></p>
<p><span><span><span><span><span><span>Please share avalanche, snowpack or weather observations via our</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/add/snow_obs"><span><span><span><span>…; </span></span></u></span></span></span></span></span><span><span><span><strong><span><u><span><span>website</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>, email (</span></span></span></span></span></span><span><span><span><strong><span><span>mtavalanche@gmail.com</span></span></strong></span></span></span><span><span><span><span><span><span>), phone (406-587-6984), or Instagram (#gnfacobs).</span></span></span></span></span></span></p>
<p><span><span><span><span><span><span>In Island Park, heavy snowfall today will create dangerous avalanche conditions on wind-loaded slopes. Fresh drifts will be easy to trigger and their additional weight could cause avalanches to break deeper in the snowpack. Cautious route finding and conservative decision making are essential. See </span></span></span></span></span></span><a href="https://www.youtube.com/watch?v=O-lUMunzE1k"><span><span><span><span><s…’s video</span></span></u></span></span></span></span></span></a><span><span><span><span><span><span> for a rundown on the aftermath of last week’s avalanche warning. </span></span></span></span></span></span></p>
Our education calendar is full of awareness lectures and field courses. Check it out: Events and Education Calendar.
Attached are a few photos of old deep slab avalanches north of town.
The second is the south face of scotch bonnet. Hard to tell the depth of the crown but it’s very visible from the lulu road, so probably pretty deep.
Attached are a few photos of old deep slab avalanches north of town.
The first photo is a south face north of round lake above 10,000’. The crown was mostly filled in but the deepest exposed part was 2-3’ deep.
