GNFAC Avalanche Forecast for Sun Feb 23, 2025
This is Alex Marienthal with the avalanche forecast for Sunday, February 23rd, at 7:00 a.m. sponsored by Polaris and Uphill Pursuits. This forecast does not apply to operating ski areas.
This morning there is a trace to 1” of new snow near Cooke City, Island Park and West Yellowstone with none elsewhere. Temperatures are 20s to low 30s F near Bozeman and Big Sky and teens to 20s F in the southern half of the forecast area. Wind has been moderate to strong from the west and southwest at 15-25 mph with gusts of 25-60 mph.
Today, temperatures will reach high 20s to mid-30s F, and gusty moderate wind will continue out of the west and southwest. Snow showers will favor Cooke City and Island Park with 6-12” possible by tomorrow morning, near Big Sky and West Yellowstone could get 3-5” with 1-3” near Bozeman.
A person can trigger large avalanches that break on weak layers buried 1-3 feet deep. These persistent slab avalanches can break hundreds of feet wide, and can be tricky as they might be triggered by the first person, or after multiple people have ridden a slope.
On Friday in the southern Madison Range there were multiple rider triggered persistent slab avalanches, one of which partially buried a rider in Tepee Basin and was triggered after their group had put multiple tracks on the slope (details and photos). Fortunately his arm and leg were visible and his partners got him out quickly and unharmed. Nearby, in the Taylor Fork, I triggered a “whumph” with a 100 ft long crack (observation), and a group of riders triggered a few avalanches from flat terrain above a steep slope (photos).
Although the likelihood and danger has decreased, the potential large consequences of these avalanches remain unchanged. Be cautious of slopes steeper than 30 degrees, particularly at middle and lower elevations, as many of these slides are happening on mid elevation slopes with trees around (Lionhead video, Black Canyon photos).
Wind Slab avalanches are an additional concern. Although their potential size is relatively small, watch for fresh drifts that grow from today’s winds and old drifts that haven’t bonded yet.
Large, human-triggered avalanches are possible and avalanche danger is MODERATE.
Across the rest of the forecast area wind slab avalanches can be triggered where strong wind the last couple days drifted snow into stiff slabs (photo).
Near Cooke City and Island Park, today’s new snow and wind will create larger drifts that might be easy to trigger. Depending on how much snow falls during the day, by this afternoon storm slab avalanches could become a problem on slopes where snow is not drifted. Warming temperatures might create density changes within the new snow that make avalanches easier to trigger. If there is more than 6” of new snow be cautious of all steep slopes, especially where even a small slide could push you into trees or over cliffs.
Wet loose avalanches are possible where above freezing temperatures melt the snow surface and make it sticky and wet. This is more likely near Bozeman and Big Sky where temperatures are warmer and there is a chance of light rain at lower elevations. Be careful of steep slopes with a wet snow surface.
Assess the snowpack for new and old drifts or a wet snow surface, and be extra cautious if there is heavy snowfall today. Human-triggered avalanches are possible and the avalanche danger is MODERATE.
Special Note - Roof avalanches
Many roofs have lots of snow on them that may come crashing down as a roof avalanche during the first big warm-up with strong sunshine. Avalanche fatalities from roof avalanches are not uncommon. Kids are especially vulnerable because they often play near houses while no one is watching.
Upcoming Avalanche Education and Events
Our education calendar is full of awareness lectures and field courses. Check it out: Events and Education Calendar
February 27, 6-8 p.m. & March 1, 10 a.m - 2 p.m. Companion Rescue Clinic. Evening lecture at REI in Bozeman. Field session at History Rock. Details and signup here.
February 28 - March 2, Bozeman Splitfest 2025 - Celebrate all things Bozeman backcountry and raise funds for GNFAC. Enjoy demos, clinics, free food and beer from MAP. Connect with fellow outdoor enthusiasts and soak up the winter stoke.
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.