Good morning. This is Alex Marienthal with the Gallatin National Forest Avalanche Forecast issued on Sunday, January 6th at 7:00 a.m. Today’s forecast is sponsored by Yellowstone Arctic Yamaha and The Friends of the Avalanche Center. This forecast does not apply to operating ski areas.
Avalanche Fatality near Choteau, MT
We are sad to report a snowmobiler was killed in an avalanche yesterday near Choteau, MT, outside out advisory area. The news report is HERE. We will share more info as it becomes available.
At 4 a.m. the mountains near West Yellowstone have 2-4” of new snow with 1” in the southern Madison Range and no new snow elsewhere. Temperatures are high teens to mid-20s F. Wind has been south-southwest at 25-35 mph with gusts of 40-60 mph. Today, temperatures will stay in the teens and 20s F. Wind will be southwest at 25-35 mph with gusts to 40 mph. Snow showers will continue to favor the mountains near West Yellowstone with 2-4” today and 3-5” overnight. By morning the rest of the mountains will have 2-4” near Big Sky and Cooke City, and 1-2” near Bozeman.
In the mountains south of Big Sky to West Yellowstone the snowpack is poorly supported by 1.5’ of weak, sugary facets on the ground (photo, video, video). Yesterday, Eric rode into Tepee Basin and found a recent snowmobile triggered avalanche. The slide was triggered near the bottom of the slope and broke a foot deep on rotten, sugary snow at the base of the snowpack (video, photo). Yesterday in the Centennial Range a similar avalanche was triggered (photo).
More snow and strong wind today will add weight and stress this weak snowpack. Avalanches will be easy to trigger and natural avalanches are possible. Avalanches can be triggered from low angle terrain below steep slopes, and as Eric describes in his video even a small slide can have fatal consequences. Avalanche danger is CONSIDERABLE and could rise to HIGH with more snow and wind today. Be conservative and avoid avalanche terrain today.
In the mountains near Bozeman and Big Sky, weak, sugary snow that formed in December is buried 1-2’ deep and creates a poor snowpack structure. We received reports of large collapses most days the past week (Activity log, photo), and yesterday in Middle Basin a skier triggered an avalanche that broke on hollow, sugary snow 1-2’ deep (photo, details). This recent activity shows avalanches breaking on this buried persistent weak layer are possible to trigger without the addition of stress from new snow. Be extra conservative with terrain selection and carefully evaluate the snowpack before travel on steep slopes. Avalanche danger is MODERATE today and could rise to CONSIDERABLE with snow and wind this afternoon.
The mountains near Cooke City have a highly variable snowpack. Some slopes are strong, others are weak without an unstable slab on top, and some slopes are unstable. Doug’s videos from last week show examples of weak and unstable slopes (video, video). No snow since last weekend and minimal wind gave buried weak layers time to adjust. Strong wind last night drifted snow into fresh slabs that might rest over buried weak layers. Today, fresh drifts are possible to trigger and more likely to break where they formed over weak snow. On non-wind loaded slopes, avalanches breaking on these weak layers are unlikely. Today, avalanche danger is MODERATE on wind loaded slopes and LOW elsewhere.
Upcoming Avalanche Education and Events
Our education calendar is full of awareness lectures and field courses. Check it out: Events and Education Calendar.
BOZEMAN
January 8, Women’s Specific Avalanche Awareness, 6:30-8 p.m. Story Mill Park, Bozeman.
January 9, 1-hr Avalanche Awareness, 7-8 p.m. Spire Climbing Center, Bozeman.
January 16, 17 and 19 or 20, Intro to Avalanches w/ Field Day, Info and Register Here.
January 23, 24 and 26, Advanced Avalanche Workshop w/ Field Day, Info and Register Here.
February 2, King and Queen of the Ridge at Bridger Bowl (fundraiser). Register with Bridger to hike in the event, and create a pledge page to raise funds with your Ridge laps.
WEST YELLOWSTONE
January 12 and 26, 1-hr Avalanche Awareness for Snowmobilers, 7-8 p.m. Holiday Inn West Yellowstone.
DILLON
January 22, 1-hr Avalanche Awareness, 6:30-7:30 p.m. U.M. Western Library.
BILLINGS
January 22, 1-hr Avalanche Awareness, 6-7 p.m. The Base Camp, Billings
COOKE CITY
Every Friday and Saturday, Rescue Training and Snowpack Update. Friday 6:30-7:30 p.m. at the Soda Butte Lodge. Saturday anytime between 10-2 @ Round Lake.
Read Doug’s recent article on Snowmobiler Education Efforts that will be published in the next issue of The Avalanche Review.