Good morning. This is Alex Marienthal with the Gallatin National Forest Avalanche Forecast on Sunday, March 10th at 7:00 a.m. Today’s forecast is sponsored by Basecamp Gallatin and Yamaha and Mystery Ranch. This forecast does not apply to operating ski areas.
This morning, there is no new snow, temperatures are teens to 20s F, and wind has been out of the southwest-west at 20-35 mph with gusts of 35-60 mph. Today, under partly sunny skies, temperatures will reach low to mid-30s F and low 40s F in the Bridger Range, and wind will be southwest at 15-30 mph with gusts to 45 mph. No snow is expected until Monday night or Tuesday.
Yesterday morning near Cooke City a snowmobiler triggered a very large avalanche on Sheep Mtn. and was partially buried (photos). In the afternoon a large natural avalanche was witnessed running on the north side of Republic Mtn. above town (photos). Both of these broke many feet deep on buried persistent weak layers, and the larger one on Sheep was 500' wide.
Similar very large avalanches have been triggered or run naturally every day since Wednesday when our last round of snowfall ended. Thursday on Henderson Mountain a snowmobiler triggered a slide that broke over 2000 ft wide, 6-10’ deep and 12-15’ at the deepest (aerial video). On Friday two more very large slides were likely triggered by snowmobilers on different sides of Scotch Bonnet Mountain (details, details, Scotch Bonnet video). There were recent natural avalanches on Scotch Bonnet (photo), and in Yellowstone National Park on Barronette (photo) and Abiathar (photo). These are only a selection among maybe the most widespread large avalanche activity I have ever seen (activity log).
Dangerous avalanche conditions exist and large human triggered avalanches are likely. Avoid riding on slopes steeper than 30 degrees and give them plenty of space if you pass beneath them. The avalanche danger is rated CONSIDERABLE.
The likelihood of triggering large, dangerous avalanches has decreased since our last round of snow, but the consequences of being caught in a slide remain high. A person can trigger slabs of wind-drifted snow or slides many feet deep on old buried weak layers. In Beehive Basin near Big Sky, on Friday skiers dropped a cornice on a slope that triggered an avalanche up to 6’ deep, 500’ wide and took out their skin track (details and photos), and yesterday a natural avalanche broke from a cornice fall (photos). On Friday in the Bridger Range on Saddle Peak skiers triggered avalanches of wind-drifted snow that were 1-2 feet deep, and one was up to 200 feet wide (details and photos). Although these avalanches were smaller than the slides in Beehive they also have large consequences, especially if they carry you over cliffs like those on Saddle Peak. Luckily nobody was caught in any of these recent slides.
Above freezing temperatures today could cause the snow surface to become wet and make wet loose avalanches and cornice falls possible. Yesterday skiers in the northern Bridger Range saw wet loose slides on sunny slopes (photo, photo). These could trigger larger avalanches that break below recent wind-drifted snow or deeper on old persistent weak layers.
If you consider riding or crossing below steep slopes, choose simple, low-consequence terrain and slopes without previous wind-loading. Carefully assess terrain above you and the potential for conditions to change as the snow surface warms and gets wet through the day. The avalanche danger is rated MODERATE.
If you venture out, please fill an observation form. It does not need to be technical. Did you see any avalanches? How much snow is on the ground? Was the wind moving snow? Simple observations are incredibly valuable. You can also contact us via email (mtavalanche@gmail.com), phone (406-587-6984), or Instagram (#gnfacobs).
Upcoming Avalanche Education and Events
Our education calendar is full of awareness lectures and field courses. Check it out: Events and Education Calendar.
THIS WEEKEND, March 8-10: Bozeman Splitfest. Check the Bozeman Splitfest website for event details and avalanche education opportunities offered by the Friends of the Avalanche Center.
Every weekend in Cooke City: Friday at The Antlers at 7 p.m., Free Avalanche Awareness and Current Conditions talk, and Saturday from 10 a.m.-2 p.m. at Round Lake Warming Hut, Free Rescue Practice.
Loss in the Outdoors is a support group for those affected by loss and grief related to outdoor pursuits. Check out the link for more information.
On Wednesday, an avalanche forecaster from the Wallowa Avalanche Center was caught and killed in an avalanche in NE Oregon (details). This tragic accident drives home the very real dangers of a life working and playing in the mountains. This is the third U.S. avalanche fatality this month (avalanche.org).