Good morning. This is Dave Zinn with the Gallatin National Forest Avalanche Forecast on Monday, December 2nd at 7:00 am. This information is sponsored by the Bozeman Ice Festival, Alpine Orthopedics & Sports Medicine and Stronghold Fabrication. This forecast does not apply to operating ski areas.
This morning, mountain temperatures are near 30 degrees F in the northern forecast area and around 20 degrees F in West Yellowstone, Island Park and Cooke City. The winds are 5-15 mph from the west to the north.
Today, high temperatures around Bozeman and Big Sky will reach 40 F, with cooler temperatures in the southern portions of the advisory area. Winds will be 5-15 mph from the west to southwest, and skies will be mostly sunny.
Skiers in Cooke City reported sneaky storms and snowfall through the second half of last week that were not picked up by the Fisher Creek SNOTEL site. Human-triggered avalanches are possible due to recent snowfall and fresh drifts of wind-loaded snow.
Triggering wind slab avalanches is the primary avalanche problem today. Avoid fresh drifts on steep slopes and look for signs of instability, including shooting cracks and recent avalanches. This problem will be most pronounced at upper elevations and wind-exposed terrain near ridgelines and gullies.
Before considering travel in avalanche terrain, dig and test the snowpack to evaluate for instability related to sugary, weak layers. We have not had reports of persistent slab avalanches in the Cooke City area; however, it is early season, and our levels of uncertainty are elevated as we learn this year’s snowpack. Slides on persistent weak layers stabilize more slowly and break deeper in the snowpack than wind slabs.
The avalanche danger is rated as MODERATE.
Human-triggered avalanches are unlikely in the mountains around Bozeman, Big Sky, West Yellowstone and Island Park. However, backcountry travelers pushing into steep and extreme terrain may encounter isolated instability and small avalanches. In these locations, a small slide has significant consequences (yesterday’s video from Beehive).
Stability is improving relative to wind slab and persistent slab avalanches. The most recent avalanche activity occurred on Friday when skiers on Mt. Blackmore intentionally triggered a small 10-foot-wide wind slab avalanche (details and photo), and a skier in Beehive Basin triggered a slide that broke 20’ wide and ran approximately 100’ over rocks (details). Reduce your exposure to steep terrain if you note signs of isolated instability, including cracking, fresh drifts or unstable test results.
ICE CLIMBERS: Today’s temperatures will climb to 40 degrees F in the Hyalite Canyon area, and the sun will come out. If the forecast holds, wet loose snow avalanche activity will increase this afternoon. These pack a powerful punch in confined gullies and will easily sweep a climber downhill. Move to cooler aspects as temperatures warm and the snow surface becomes wet or pinwheels.
The avalanche danger is LOW. Follow the fundamentals of safe backcountry travel.
In the afternoon, the danger of wet snow avalanches will rise to MODERATE in the Bridger, North Madison, and North Gallatin Ranges.
Upcoming Avalanche Education and Events
Our education calendar is full of awareness lectures and field courses. Check it out: Events and Education Calendar
TODAY, Monday, December 2, 6:30 p.m. MAP community partnership night and Free 1-hr Avalanche Awareness at MAP Brewing
Tuesday, December 10, 9 a.m.-3 p.m., West Yellowstone Avalanche Fundamentals: Motorized Guide Cert Course, Pre-registration required.
For an intro class with a field day, Register for our Avalanche Fundamentals course.
Friends of the Avalanche Center: Fall Fundraiser!
We’re still counting on your support and the online Fall Powder Blast fundraiser is 77% of the way to our goal. Please consider making even a small donation HERE or via Venmo
While stability is improving during this period of high pressure, the snowpack structure is deteriorating, becoming weaker and more faceted. Enjoy the relative stability for now and prepare to recalibrate to more dangerous conditions the next time it snows.
Bridger Bowl has backcountry conditions, and there are no ski patrol services. While they set up for the season, please steer clear of snowmaking equipment, chairlifts, and snowmobiles and respect posted signage.