Good morning. This is Alex Marienthal with the Gallatin National Forest Avalanche Forecast on Sunday, December 4th at 7:00 a.m. This information is sponsored by Gallatin Valley Snowmobile Association, Beartooth Powder Guides and Chad Bunting-Financial Advisor-Edward Jones. This forecast does not apply to operating ski areas.
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*Note: Bridger Bowl Ski Area is closed and there are no avalanche control or ski patrol services. Backcountry conditions exist. Please don’t ski over hoses and power cords, stay off chairlifts, and give snowcats and snowmobiles plenty of room.
This morning there is no new snow. Temperatures are teens to low 20s F. Wind has been out of the west-southwest at 10-20 mph with gusts to 35 mph. Today temperatures will be in the 20s F. Wind will be west-southwest at 10-20 mph, and will increase to 20-30 mph with the arrival of snow showers this afternoon. Snow will last through tonight with 4-8” possible by morning.
Yesterday morning riders reported a large natural avalanche on Lionhead Ridge that occurred the prior night (photos and details). Wednesday through Friday, the mountains received over two feet of snow accompanied by strong winds which caused large avalanches to break naturally on Thursday through early yesterday (photos). Recent natural avalanches indicate buried persistent weak layers were pushed to their breaking point, and today human-triggered avalanches remain likely. Dangerous avalanche conditions exist and avalanche danger is CONSIDERABLE. Cautious route finding and conservative terrain selection are essential.
Between Wednesday and Friday over two feet of snow fell accompanied by strong winds. This rapid addition of weight to the snowpack created large, 3-4 foot deep natural avalanches on all aspects (details and photos). With clear skies yesterday, riders saw natural avalanches on Sheep Mountain and Fox Mountain that likely broke Friday morning. I was riding near Cooke City two days ago and found buried weak layers that I suspect contributed to recent avalanche activity (video from Friday). The likelihood of triggering a large avalanche has decreased, but the consequences are high. Large, human-triggered avalanches are possible and danger is MODERATE. Danger may increase this afternoon if snowfall is heavy.
Six inches to a foot of snow fell on Thursday and Friday, and strong wind drifted this snow into thicker slabs. These wind slabs are possible to trigger, especially where they formed on top of buried weak layers (Taylor Fork video, Bacon Rind observation). Snow and wind this afternoon may create fresh, unstable wind slabs. Be cautious of drifts of snow on steep slopes and dig down to check for buried weak layers before riding steep slopes. Human-triggered avalanches are possible and the avalanche danger is MODERATE.
If you get out, please share avalanche, snowpack or weather observations via our website, email (firstname.lastname@example.org), phone (406-587-6984), or Instagram (#gnfacobs).
Island ParkWe are not issuing danger ratings.
Upcoming Avalanche Education and Events
Our education calendar is full of awareness lectures and field courses. Check it out: Events and Education Calendar.
Monday, December 5, 6:30-7:30 p.m. @MAP Brewing in Bozeman, Know Before You Go avalanche awareness presentation.
Tuesday, December 6, 9 a.m. - 3:00 p.m. West Yellowstone Avalanche Fundamentals w/ Snowmobile Field Session. Pre-register HERE.
Thursday, December 8, 6 - 7:30 p.m., Free Snow & Avalanche Safety Workshop: Belgrade Community. This workshop will cover the basics of snow and avalanche equipment. Belgrade Community Library. A raffle and pizza will be included!
Monday, December 12, 5-8 p.m. @MAP Brewing, Movie Night.
Tuesday, December 13, 6 p.m., Avalanche Awareness + Beacons at Story Mill Park. Free.