This is Alex Marienthal with the avalanche forecast for Saturday, January 4th, at 7:00 a.m. sponsored by Uphill Pursuits and Polaris. This forecast does not apply to operating ski areas.
Since yesterday morning snowfall amounts are:
- 4-5” (0.4-0.5” snow water equivalent (SWE)) in Cooke City, Bridgers, Big Sky.
- 2-3” (0.2-0.3” SWE) in Hyalite, Taylor Fork, West Yellowstone, Island Park:
Temperatures are low 20s to low 30s F this morning, and will be in the 20s F today. Wind has been out of the southwest, and increased overnight to 5-20 mph with gusts of 35-45 mph. Today the wind will shift and be from the northwest at 5-15 mph with gusts to 20 mph.
Another round of snowfall is starting this morning, favoring the mountains near Bozeman and Big Sky with heavy snow possible during the day. By this evening, 4-8” of snow could fall in the Bridger Range, Hyalite and near Big Sky with 2-3” elsewhere.
All Regions
Across our forecast area dangerous avalanche conditions exist. Frequent snowfall over the last 2 weeks has built thick, heavy slabs of snow above weak layers that are now buried 2-4 feet deep. Human triggered avalanches are likely, and can be large enough to bury a person, or possibly larger. Where snowfall is heavy this morning the likelihood of triggering an avalanche will increase during the day, and natural avalanches are possible.
Near Cooke City received 13” of heavy snow from Thursday to yesterday afternoon which prompted an avalanche warning yesterday, and there was a big natural avalanche on Sheep Mtn. which broke 4 feet deep and hundreds of feet wide. During the last round of snow, there were similarly large natural avalanches on Henderson Mountain and Sunset Peak. This type of persistent slab avalanche is similar to what you can trigger today.
Yesterday Mark snowmobiled in Cabin Creek near West Yellowstone where he had widespread collapsing and saw relatively large avalanches on road cuts (video and observation with photos). These are clear signs that a person can easily trigger an avalanche on slopes steeper than 30 degrees, or from flatter terrain connected to steep slopes. We have received daily feedback that the snowpack is unstable via collapsing, whumpfs, and avalanches. Check out our observations page to view the latest reports of these red flags.
Winds have been generally light with the recent snowfall, so there is plenty of soft snow to be drifted into slabs by any increase in wind speed. Last night a few wind slabs probably formed from moderate southwest winds. These can be a hazard on their own, and increase the chances of triggering larger persistent slab avalanches on wind-loaded slopes.
Yesterday’s snow fell as temperatures warmed which caused heavier snow to form slabs over lower density snow. This setup caused storm slab avalanches to break within the new snow (Bridgers observation). These slabs typically stabilize quickly, but a few might remain unstable today. Cracking across the snow surface is a sign you could trigger slabs of new or wind-drifted snow.
Enjoy the new snow while staying on slopes less than 30 degrees, and away from flatter terrain below these steep slopes (Ian’s video). New snow and buried weak layers make human-triggered avalanches likely today, and the avalanche danger is CONSIDERABLE throughout the forecast area.
Upcoming Avalanche Education and Events
Our education calendar is full of awareness lectures and field courses. Check it out: Events and Education Calendar
Wednesday, January 8, 2025, 7-9:30 p.m., Avy Savvy Night at the Colonial Theater, Idaho Falls. More information HERE.
We offer Avalanche Fundamentals with Field Session courses targeted towards non-motorized travelers VERY SOON in January and one geared towards motorized users. Sign up early before they fill up.
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.
THANK YOU - Fall fundraiser
On behalf of the Friends of the Avalanche Center, we would like to extend our heartfelt thanks for your generous support of the Powder Blast fundraiser. This is our largest fundraiser of the year. We are thrilled to share that, thanks to your contributions and the incredible generosity of an anonymous donor, we have successfully met our fall fundraising goal.
There were two recent avalanche deaths in Utah involving solo travelers. One on Saturday but recovered on Tuesday (initial report), and a splitboarder traveling solo on Tuesday (initial report). Traveling alone in avalanche terrain carries significant additional risks.