GNFAC Avalanche Forecast for Fri Feb 21, 2025
This is Ian Hoyer with the avalanche forecast for Friday, February 21st, at 7:00 a.m. sponsored by Yellowstone Club Community Foundation and Montana State Parks. This forecast does not apply to operating ski areas.
This morning, winds are generally light (5-10 mph). Except for in the Bridger Range, where they picked up overnight and are blowing 20-25 mph out of the west, with 40 mph gusts. There is no new snow. Temperatures are in the teens and low 20s F.
Today will have generally calm winds (again, excepting the Bridger Range, where moderate west winds with stronger gusts will continue). Temperatures will rise into the high 20s and low 30s F. Skies will be mostly sunny in the north, with increasing clouds as you go further south in our advisory area. No new snow is expected.
Persistent Slab avalanches are the primary concern. These slides will break 1-3 ft deep on weak layers that formed at the snow surface in late January. They can be triggered from a distance or the bottom of a slope, as demonstrated by slides triggered on Wednesday near Lionhead (video) and in the Black Canyon area (east of Island Park, outside our advisory area). These weak layers don’t exist on all slopes, but they are widespread enough that all slopes should all be presumed guilty, until proven innocent (by digging multiple snowpits without finding the weak layer). Triggering large avalanches is LIKELY if you get on or near slopes steeper than 30 degrees.
Wind Slab avalanches are a more isolated concern, but there are probably still some places where drifts have formed and aren’t well bonded so you could trigger one. Temperatures won’t be too warm in these areas, so I don’t expect widespread wet loose activity, but it’s worth being on alert for if the sun pops out.
Conditions remain dangerous. The avalanche danger is CONSIDERABLE.
With winds picking up overnight, Wind Slab avalanches are the primary concern. There is lots of soft snow available for transport so expect deep drifts that will be easily triggered today. Keep watch for visual clues of drifted snow and steer clear of bulbous pillows that will generally have formed below ridgelines and cornices. Avoiding windloaded slopes will dramatically decrease your chance of triggering a large avalanche today.
Strong winds may limit melting at upper elevations, but on slopes that aren’t cooled by the winds, expect Loose wet avalanches as the day heats up and direct sunshine melts surface snow.
The avalanche danger is CONSIDERABLE on windloaded slopes and MODERATE on all other slopes.
The concerns in these areas are the same as in the Bridger Range, but winds are lighter this morning. This means that fresh wind slabs will be more isolated and Wind Slab avalanches not as easily triggered. Be on the lookout for those fresh wind slabs or older wind drifts that haven’t yet bonded to the snow beneath them.
Be on alert for Wet Loose avalanches as the day heats up. Cold powder from the last week will be seeing direct sunshine and warm temperatures for the first time today on many slopes. With lots of fresh snow, these slides may gain enough volume to really push you around or bury you in a gully.
The avalanche danger is MODERATE today.
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.