Debris from a large natural avalanche on the West side of the Bridgers behind Bridger Bowl on morning of 1/24. The debris has a lot of small trees that the avalanche broke and carried to the bottom. Photo: BBSP
<p>I'm happy to say it looks and feels like winter in the backcountry. Accumulating snowfall has been recorded somewhere across the forecast area for ten consecutive days. The last storm favored the mountains near Bozeman and Big Sky, but in the big picture, most areas have picked up 2+ feet of snow in the past week. Consistent snowfall has also produced consistent signs of instability. Our <a href="https://www.mtavalanche.com/avalanche-activity">activity log</a> indicates cracking/collapsing or avalanches have taken place somewhere in the forecast area for eight consecutive days. </p>
<p>Today, there are two main avalanche problems to look out for. The first and primary problem is wind loaded slopes. Moderate to strong west-northwest winds have blown new snow into dense slabs 1-2’ thick (<strong><a href="https://www.mtavalanche.com/images/19/collapsing-history-rock">photo</a…;). This problem is most prevalent below upper elevation ridgelines, rockbands and cross loaded terrain features (<strong><a href="https://www.mtavalanche.com/images/19/wind-loaded-slope-buck-ridge">pho…;). Yesterday, I rode Buck Ridge south of Big Sky and found wind loaded slopes to be the primary avalanche concern (<strong><a href="https://www.youtube.com/watch?v=VVFaUMY0NQg&list=PLXu5151nmAvRNl9ku…;). With more snow and wind in the forecast, wind loaded slopes will be easy to trigger and have the potential to fail naturally.</p>
<p>The second problem is avalanches failing on persistent weak layers buried mid-pack or near the ground. In the mountains near West Yellowstone, this problem exists on all aspects and elevations (<strong><a href="https://www.youtube.com/watch?v=VVFaUMY0NQg&list=PLXu5151nmAvRNl9ku…;). In the northern mountains and Cooke City, this problem is not as widespread, but exists mainly where the snowpack is less than 3’ deep (<strong><a href="https://www.youtube.com/watch?v=orGDvzUtVcw&list=PLXu5151nmAvRNl9ku…;). Yesterday in Hyalite, two separate groups of skiers experienced thunderous collapses and shooting cracks on lower elevation slopes where the snowpack is shallow and weak (<strong><a href="https://www.mtavalanche.com/images/19/shooting-cracks-hyalite">photo</a…;,). In the Bridger Range, large natural avalanches were observed on the west side which typically has a weaker snowpack. One slide broke hundreds of feet wide, 2-4’ deep, and ran full track (<strong><a href="https://www.mtavalanche.com/images/19/west-side-bridger-avalanche">phot…;). These slides likely failed on a layer of sugary facets a foot or two above the ground. The best defense against a persistent weak layer problem is to avoid riding on or underneath slopes steeper than 35 degrees. </p>
<p>Today, the combination of new snow, wind, and buried weak layers make human triggered avalanches likely and the avalanche danger is rated <strong>CONSIDERABLE</strong>.</p>
Saturday, February 2 at Bridger Bowl. This is the Friends of the Avalanche Center’s second biggest fundraiser of the year. Come on out and help us raise some money by hiking and skiing some laps on the ridge. Prizes, camaraderie and a good time is guaranteed.
Avalanche fatality in Tobacco Root Mountains
Four skiers were ascending a steep, heavily treed slope and triggered a large avalanche. The two skiers highest on the slope grabbed trees, and the lower two were caught and partially buried. One died from trauma at the site, and the other was air-lifted to emergency care with serious injuries. (A more detailed accident report will be available soon. Check back in a day or two.) Our deepest condolences go out the family and friends of the victim.
"Cracking/Whumphing observed on open east aspect at ~7300' in the main fork of Hyalite Canyon. We also observed what we suspect was a powder cloud across the canyon in the terrain above the Dribbles/Responsible Family Men around midday. It was difficult to be sure looking through the trees."
Skiers up the main fork of Hyalite Canyon experienced collapsing and shooting cracks on an east facing slope at 7.300 ft. Photo: M. Tepfer
A foot of new snow and strong west-northwest winds are creating dangerous avalanche conditions on wind loaded slopes. Facets near the ground are gaining strength, but slides failing this layer can't be ruled out. With more snow and wind on the way, the avalanche danger will remain elevated. Photo: GNFAC
A skier noticed multiple collapses at History Rock, and snapped a photo of active wind loading at higher elevations in Hyalite. From the email: " Roughly 30cm new snow from the last storm, light winds, although Blackmore (pictured) and Flanders appeared to be getting hammered by the wind. Did a few laps in the top meadow and was getting frequent collapsing on the way back up. One felt like a small earthquake and was the loudest wumpf I've ever heard." Photo: M. Lavery
