Good morning. This is Alex Marienthal with the Gallatin National Forest Avalanche Forecast on Monday, March 7th at 7:00 a.m. This information is sponsored by Community Food Co-op, Bridger Bowl and Yellowstone Ski Tours. This forecast does not apply to operating ski areas.
Since yesterday morning the mountains near Bozeman and Big Sky got a trace to an inch of low density snow with none elsewhere. This morning, temperatures are single digits below and above zero F, and wind is from the northwest-west at 5-20 mph with gusts of 20-30 mph. Today temperatures will reach teens to low 20s F with moderate west-northwest wind at 15-30 mph. Snow will arrive tonight and stay through Wednesday. By tomorrow morning 4-6” of new snow is possible throughout the forecast area.
Yesterday riders saw a recent snowmobile triggered avalanche that broke 2 feet deep and more than 100 feet wide on Scotch Bonnet Mtn. (photo and details). A couple weak layers of snow which formed in January and early February are buried 1-2 feet deep and make large avalanches possible to trigger. We have seen regular avalanche activity on these layers over the last two weeks (weekly update video, activity log). Most recently, on Thursday natural avalanches broke ~100 feet wide in Republic Creek, Hayden Creek, Sheep Creek (photo, details) and Pebble Creek (photo, photo), on Friday skiers triggered an avalanche remotely from a low angle ridgeline above the slope (photo), and on Saturday skiers had a large collapse of the snowpack on low angle terrain (details).
Today avalanches can break at least 1-2 feet deep, up to a couple hundred feet wide, and can be triggered from lower angle slopes that are connected to steep slopes. Before you travel on or underneath steep slopes carefully assess the snowpack for unstable buried weak layers, and assess the consequences of being caught in an avalanche. Today avalanches are possible and avalanche danger is MODERATE.
Large avalanches are unlikely near Bozeman, Big Sky and West Yellowstone. Be on the lookout for isolated areas of instability like where hard slabs of wind-drifted snow sit on top of weak snow buried 6-18” deep. During recent field days we saw the weak snow that we’ve been talking about since January will still be a problem when we get more snow (Buck Ridge video, Lionheaad video). The last reported avalanches on these weak layers were last weekend. A lack of snow over the last week allowed the snowpack to become more stable without added stress. Yesterday in Hyalite, skiers had a small wind slab crack under their skis while they descended from a high ridgeline (photo and details). Increased northwest-west wind today will drift a few inches of recent snow into some very small, fresh soft slabs. These could be hazardous if they knock you off your feet in high consequence terrain.
Watch for cracking of the snowpack around your feet or skis as a sign fresh drifts may be unstable. If you plan to ride on steep slopes, carefully assess the snowpack to be sure there is not weak snow buried below a thick slab of snow. Today the avalanche danger is LOW. Expect danger to increase with new snow over the next couple days.
Upcoming Education Opportunities
See our education calendar for an up-to-date list of all local classes. Here are a few select upcoming events.
Every Saturday near Cooke City, 10 a.m.-3 p.m. FREE snowpack update and transceiver/rescue training. Stop by for 20 minutes or more at the Round Lake Warming Hut.
Daves Zinn’s latest article, Understanding what digital slopes angle maps can (and can’t) tell you, is a great read for anyone using apps to identify avalanche terrain.