"Similar to your complete ripout of the slope at the head of first yellow mule, this aspect pulled out naturally likely on the 25th - natural caused. No tracks around." Photo: TJ Krob
<p><span><span><span><span><span><span>On many steep slopes the added weight of a person will easily trigger an avalanche. Sugary facets and surface hoar make up the bottom of the snowpack, and these weak layers can barely support overlying slabs of snow that accumulated through January. Over the last week, no snow fell in the Bridger Range and a few inches accumulated elsewhere. Despite minimal recent loading, the very weak snowpack is slow to stabilize and human triggered avalanches are likely. </span></span></span></span></span></span></p>
<p><span><span><span><span><span><span>A long list of avalanche activity over the past three weeks shows examples of the potentially deadly slides that remain likely, and why we are hesitant to trust steep slopes (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/avalanche-activity"><span><span><span><stro… activity</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>). This list includes, but is not limited to: </span></span></span></span></span></span></p>
<ul>
<li><span><span><span><span><span><span>A couple slides triggered by skiers on Saddle Peak last week (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/30261"><span><span><span><strong><span…;, </span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/30161"><span><span><span><strong><span…;). </span></span></span></span></span></span></li>
<li><span><span><span><span><span><span>Large natural avalanches near Cooke City (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/30282"><span><span><span><strong><span…;).</span></span></span></span></span></span></li>
<li><span><span><span><span><span><span>Large slides on Buck Ridge near Big Sky (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/30299"><span><span><span><strong><span…;).</span></span></span></span></span></span></li>
<li><span><span><span><span><span><span>Multiple avalanches triggered remotely ( </span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/30257"><span><span><span><strong><span… City 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/30263"><span><span><span><strong><span… City 2</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/30267"><span><span><span><strong><span… City 3</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/30196"><span><span><span><strong><span… Ridge avalanche</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>).</span></span></span></span></span></span></li>
<li><span><span><span><span><span><span>Near Lionhead on Friday we saw dozens of avalanches that occurred on all aspects and elevations at various times over the last week, some as recent as Thursday (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/30278"><span><span><span><strong><span… and 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=LKXiHCgovsk&list=PLXu5151nmAvSH326z…;
</ul>
<p><span><span><span><span><span><span>Careful route selection is essential. Be cautious of travel near and underneath steep slopes, especially those that were previously wind-loaded (</span></span></span></span></span></span><a href="https://www.youtube.com/watch?v=7AjZ2ip_A8E&list=PLXu5151nmAvSH326z… video</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>). Find terrain that is less than 30 degrees steep and not directly below or connected to anything steeper (</span></span></span></span></span></span><a href="https://www.youtube.com/watch?v=_d5_vlY-bjg&list=PLXu5151nmAvSH326z… about terrain assessment</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>). Human triggered avalanches are likely and the avalanche danger is CONSIDERABLE.</span></span></span></span></span></span></p>
<p><span><span><span><span><span><span>Today’s above freezing temperatures could bring a threat of <u>wet snow avalanches</u>, mainly near Bozeman and Big Sky on slopes receiving direct sunshine. Wet avalanches should be minimal today, and might become more of a concern later in the week. A sticky snow surface or rollerballs on steep slopes are the first sign of decreasing wet snow stability.</span></span></span></span></span></span></p>
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"Starting at 45°11'13.26"N / 111°27'36.92"W, the NNE slope slid (likely rider caused 2 days ago).
The adjacent slopes at 45°11'18.09"N / 111°27'54.78"W further west were slightly newer perhaps the 26th or late on the 25th. Each ripped down to the ground at the crown." Photo: TJ Krob
ETCP 7. Broke on top of the facet layer mid pack. Only change that was noticeable from last week is the warming from the bottom up of the snow pack making nerd candy sized facets on the base of the pack. Domino surface hoar between facet layers not as present. 28degree slope. Fracturing present on roll over below into middle. Pit was dug down the ridge from the cornice release slide east side of prayer flags from last weekend.
1/20/2024 ETCP7. Facets were smaller and surface hoar layer domino layer between the bottom 8in facet layer and next 8in facet layer present. Pit dug east side prayer flag up the ridge from cornice release into middle.
Starting at 45°11'13.26"N / 111°27'36.92"W, the NNE slope slid (likely rider caused 2 days ago).
The adjacent slopes at 45°11'18.09"N / 111°27'54.78"W further west were slightly newer perhaps the 26th or late on the 25th. Each ripped down to the ground at the crown. Severe instability was present even when cresting over the slope from the entrance through the regular access to cedar - still not broke open.
Similar to your complete ripout of the slope at the head of first yellow mule, this aspect pulled out naturally likely on the 25th - natural caused. No tracks around.
We skied in the Bridger Range where unstable snow was not widespread, but does exist on previously wind-loaded slopes. Weak snow exists on all slopes, and where a wind slab sits over this weak snow you can trigger a dangerous avalanche. Attached pit profile from Hourglass shows a wind loaded slope, and other pit profile is in more sheltered terrain.
Slopes without a slab on top of the weak snowpack are less likely to produce a slab avalanche, but even the slightest bit of a supportable slab could easily break on the weak snowpack. Also, the sugary, weak snowpack is easily entrained by smaller slides causing more powerful loose snow slides on sustained steep terrain.
Wind was moderate at the ridge, but not transporting any snow. Light wind below the ridge. Temps near to above 0 C. Broken to Overcast skies.
Whumping on approach when not is snowmobile tracks. Dug a pit on a north east face slope off the Miller creek road approach to daisy pass at ≈ 9000ft . Shallow snow pack 110cm. Ectp 10 60 cm from ground 26 deg slope. Choose to ski low angle south west facing slope with no terrain above. No recent natural slides were observed.
Started noticing cracking, collapsing, and whumfing around 7800' on east-facing slopes. ECTP 11 on our stability test.
