On February 6, 2022, one snowmobiler in a group of four was caught and killed in a small avalanche on Ski Hill at the south end of Lionhead Ridge. He was on a 45-degree wind-loaded slope when it released and partially buried him against a tree. The slide was 4"-11" deep, 75 feet wide and ran 300 vertical feet on a layer of near-surface facets.
From the Gallatin NF Avalanche Center:
We rode up Yale Creek, then to the Mt. Jefferson Bowl, then to Tin Cup Pass north of Mt Raes. We saw no avalanche activity or signs of instability. It was calm out and the wind was not moving snow. The debris piles on Mt. Jefferson were from an avalanche cycle the end of December and they are still visible. January has been dry!
Our stability test did not break on the surface hoar. There needs to be more snow on top of it. Possibly on a wind drifted area, but in general, the stability is good until we get more snow.
<p>Alex has been in Cooke City since Sunday after 12-14” fell; lucky boy. He and others noted natural and human triggered avalanches under the new snow where a thick layer (6+”) of weak snow (facets and surface hoar) continues to show signs of instability. Our <a href="http://www.mtavalanche.com/avalanche-activity"><strong><u>Avalanche Activity List</u></strong></a> documents 9 events in one week. Yesterday, as Alex skied, he witnessed shooting cracks, a whumpf and another day of propagating test scores in his <a href="http://www.mtavalanche.com/snowpits"><strong><u>snowpits</u></strong></…;. His latest <a href="https://youtu.be/EQDLaHsyinU"><strong><u>video</u></strong></a> is an instructive show-and-tell of avalanche concerns. </p>
<p>Before Friday and Saturday’s storm, stability was good and people were feeling comfortable getting into serious avalanche terrain. Today, not so much. Avalanches are possible on the same slopes that were stable a week ago. We have a significant weak layer that has 1.5 feet of snow on top of it. Any slope that has a wind-load will be especially worrisome. Change objectives and stay clear of avalanche terrain at the first sign of instability, like Alex did yesterday. The weak layer is not going away and slopes still need time to adjust to the added weight of the weekend’s snow. For today, the avalanche danger is rated MODERATE on all slopes.</p>
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<p>The snowpack from the Bridger Range to West Yellowstone is generally stable. Most slopes have weak, sugary snow (and/or feathery surface hoar crystals) buried 18” under the surface. Without the weight of new snow this layer will remain dormant, but there are a few exceptions. Sprinkled throughout the forecast area are small, unstable slopes from wind drifting. Thicker, meatier drifts of snow could break on this weak layer. This is what occurred in Lionhead on Sunday. A snowmobiler triggered a small, shallow and very steep wind-loaded slope that carried him into trees and buried him (<a href="http://www.mtavalanche.com/node/25766"><strong><u>details</u></strong><…;). Even in a sea of stability there are a few shoals of danger lurking. There always are. A telltale sign of instability associated with wind-loading are cracks shooting out from skis or a sled. For today, given the lack of new snow and overall stability, avalanches are unlikely and the danger is rated LOW. </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><u>websi…;, email (<a href="mailto:mtavalanche@gmail.com"><strong><u>mtavalanche@gmail.com</u></str…;), 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
TOMORROW, February 10th, Forecaster Chat at Uphill Pursuits, “Beyond the Beacon”, 6:30 p.m., with GNFAC forecaster Dave Zinn.
Crown of the avalanche on Ski Hill. The snow rangers in the photo are standing near the victim burial site. Photo: GNFAC
Looking up from the bottom of the avalanche that killed one snowmobiler on Ski Hill. The crown is visible at the top of the hill. The men in the photo are standing near the trees where the victim was buried. Photo: GNFAC
