Good morning. This is Ian Hoyer with the Gallatin National Forest Avalanche Forecast on Friday, December 8th at 7:00 a.m. This information is sponsored by the Bozeman Ice Festival, Knoff Group Real Estate, and Werner Wealth Management (Advisors with DA Davidson). This forecast does not apply to operating ski areas.
Bridger Bowl is opening the lower mountain Friday (Today) through Sunday. Uphill travel is permitted from a backcountry gate at the top of the Sunnyside Quad. Backcountry conditions exist above the Quad with no avalanche mitigation or ski patrol services. Call 911 for rescue
A quick burst of intense snowfall yesterday morning brought 11” of new snow to the Bridger Range, 7-8” near Big Sky and Hyalite, and 5-6” across the rest of the advisory area. Mountain temperatures are in the teens F this morning and will rise into the 20s F. As the snow fell yesterday morning winds were intense out of the west, with gusts of 40-55 mph and an 87 mph gust on the Bridger Ridge. Winds are more moderate this morning and will remain at 10-20 mph today, shifting from west to northwest. Snow showers today and tonight will add up to 1-3” of new snow in most places by tomorrow morning. Big Sky and Hyalite look like they’ll do a bit better with 3-6” accumulating.
Human triggered avalanches are likely today across our advisory area. New and wind drifted snow sitting on top of weak snow that fell in October and early November make for an unstable combination. Conditions are much less dangerous where this new snow fell onto dirt.
The snowpack situation is relatively simple, but that doesn’t diminish its danger. Any slope that was snow covered before last weekend has the recipe for an avalanche. Unfortunately, this includes essentially any slope that has enough snow to ski or ride. You’ll find more of these slopes with weak snow at higher elevations and in the southern part of our advisory area. Our recent field videos from Island Park, Cooke City, and Lionhead illustrate the setup. As Doug identified in his video yesterday from Hyalite you can even find these conditions in snowy gullies surrounded by bare ground (Hyalite video). The deeper the new snow is, the touchier and more dangerous conditions will be. Drifts from yesterday’s high winds have piled new snow up even more deeply.
Clear signs of instability were noted across the advisory area yesterday as heavy snow fell. Dave and I felt collapses (whumpfs) in Island Park (observation). Big Sky Ski Patrol reported large natural avalanches in closed terrain with a snowpack similar to the surrounding backcountry (photo) and a skier triggered an avalanche in a backcountry snowpack at Bridger Bowl (photo). Expect to trigger similar slides today if you get onto steep slopes.
We have a long winter ahead of us, keep your early season excitement in check and make appropriately conservative decisions. Avoid traveling on or beneath slopes steeper than 30 degrees today. The avalanche danger is CONSIDERABLE in the mountains near Bozeman, Big Sky, West Yellowstone, Island Park, and Cooke City.
If you venture out, please fill an observation form. It does not need to be technical. Did you see any avalanches? How much snow is on the ground? Was the wind moving snow? Simple observations are incredibly valuable. You can also contact us via email (firstname.lastname@example.org), phone (406-587-6984), or Instagram (#gnfacobs).
Upcoming Avalanche Education and Events
Our education calendar is full of awareness lectures and field courses. Check it out: Events and Education Calendar.
Tuesday, December 12th, 9:00 a.m. to 3:00 p.m., West Yellowstone Motorized Avalanche Fundamentals, Pre-registration and more information HERE.
We offer Avalanche Fundamentals with Field Session courses targeted towards non-motorized users in December and January and one geared towards motorized users in January. Sign up early before they fill up.
Loss in the Outdoors, is a support group for those who have been affected by grief and loss related to outdoor pursuits. Check out the link for more information.
Listen to GNFAC Forecaster Dave Zinn on the Hoary Marmot Podcast for some extracurricular avalanche talk (link to episode).