Several natural avalanches spotted from Big Sky Ski Resort on 5 January 2021. Photo: H. Claiborne
<p>There is an Avalanche Warning in effect for the Bridger Range, Southern Gallatin Range, Southern Madison Range, the Lionhead area near West Yellowstone and the Centennial Range near Island Park, ID. Heavy snowfall overnight brought 8-10” of new snow with 0.8-1.0” of <a href="https://www.nrcs.usda.gov/wps/portal/nrcs/detail/or/snow/?cid=nrcs142p2… water equivalent</a> (SWE). New snow and strong winds are overloading a weak snowpack and creating very dangerous avalanche conditions. Natural and human triggered avalanches are very likely.</p>
<p>Watch our recent videos from <a href="https://www.youtube.com/watch?v=KLSgnetPsDg">Lionhead</a>, <a href="https://www.youtube.com/watch?v=ewdpClMTkwU&list=PLXu5151nmAvQDzKmH… Fork</a> and <a href="https://www.youtube.com/watch?v=1ihnOqeMkLc&list=PLXu5151nmAvQDzKmH… Peak</a> to learn more about similarly weak snowpack structure in each of these areas.</p>
<p>Avalanche terrain and avalanche runout zones should be avoided. The avalanche danger is rated <strong>HIGH</strong> on all slopes.</p>
<p>The Northern Madison Range received 9” of snow overnight with 0.6 SWE and the Northern Gallatin picked up 4” with 0.4 SWE. This snow is loading a weak foundation of sugary facets and sustained 25-35 mph winds from the southwest are creating unstable drifts that are likely to avalanche under the weight of a skier or rider. Recent avalanches in Hyalite Canyon are examples of what we are worried about triggering today (<strong><a href="https://www.mtavalanche.com/node/23524">ice climber triggered avalanche details</a>, <a href="https://mtavalanche.com/node/23543">natural avalanche details</a></strong>). With unusually strong winds, expect these unstable drifts to be in unusual locations. On Sunday, my partner and I did not witness any red-flags such as collapsing or recent avalanches in Beehive but we did find fistfuls of sugary facets near the bottom of the snowpack that failed in stability tests and are likely to produce avalanches under the weight of the new snow (<strong><a href="https://www.youtube.com/watch?v=l6Ppy9Eyy_4&list=PLXu5151nmAvQDzKmH…;
<p>Cautious route finding, thorough snowpack assessment and conservative decision-making are essential today as human-triggered avalanches are likely. The danger is rated CONSIDERABLE.</p>
<p>Cooke City lacks the widespread weak layers of the other ranges in our advisory area. The avalanche danger increased with 6” of new snow overnight (0.6” SWE) and recently wind-drifted snow. Recent avalanches on Abiathar and Crown Butte are examples of the instabilities you should be assessing for and avoiding (<a href="https://www.mtavalanche.com/node/23512"><strong>photo and details</strong></a><strong><u>,</u></strong> <a href="https://www.mtavalanche.com/node/23505"><strong>photo and details</strong></a>, <a href="https://youtu.be/UEY5A4YXibg"><strong>video</strong></a>).</p>
<p>Carefully assess the snowpack by digging a snowpit and performing a stability test to see if you found an area with a weaker snowpack and avoid area of wind-drifted snow. The danger is rated MODERATE and human-triggered avalanches are possible.</p>
<p>If you get out, please send us your observations no matter how brief. You can submit them via our <a href="https://www.mtavalanche.com/node/add/snow_observation"><strong>website<…;, email (<a href="mailto:mtavalanche@gmail.com"><strong>mtavalanche@gmail.com</strong></a…;), phone (406-587-6984), or Instagram (#gnfacobs).</p>
See our education calendar for an up to date list of all local classes. Here are a few select upcoming events and opportunities to check out:
AVALANCHE WARNING for Bridgers, S. Gallatin, S. Madison, Lionhead and Centennials.
A backcountry skier wrote, "...observed a fairly large, cornice-triggered avalanche on an east aspect at 9600’ that looked to be several hours old. The crown was 40-100 cm deep, and it looked like it failed about 20 cm into the facets that make up the lower half of the snowpack in this region."
A backcountry skier wrote, "...observed a fairly large, cornice-triggered avalanche on an east aspect at 9600’ that looked to be several hours old. The crown was 40-100 cm deep, and it looked like it failed about 20 cm into the facets that make up the lower half of the snowpack in this region."
From obs: "... in the Crazy Mountains. Observed heavy NE cornicing as well as complex wind transport. Lots of stripped N aspects. Conditions deteriorated throughout the day with high winds and graupel deposition. Our 100cm depth pit was on a 240º SW aspect at 8000 feet, a 20º slope angle,... We performed an ECT and received an ECTX result. We performed a isolated column test and received a CTH - 22 RP Q2, fracturing 30cm below the top on a layer of facets...." Photo: H. Darby
