GNFAC Avalanche Forecast for Mon Dec 14, 2020

Not the Current Forecast

Good Morning. This is Alex Marienthal with the Gallatin National Forest Avalanche Forecast on Monday, December 14th at 7:15 a.m. This forecast is sponsored by Yellowstone Club Community Foundation and Knoff Group Real Estate. This forecast does not apply to operating ski areas.

*Note: Bridger Bowl Ski Area is closed and there is no avalanche control or ski patrol services. Backcountry conditions exist. Workers are setting up for the season and making snow. Please stay clear of work areas, snow guns, chairlifts and other equipment.

Mountain Weather

At 6 a.m. the mountains have 1-3” of new snow. Wind is west-southwest at 5-15 mph with gusts to 25 mph and temperatures are single digits to teens F. Today temperatures will reach high teens to low 20s F with west-southwest wind at 5-15 mph. Light snow through this morning will drop 1-2”. The next round of snow arrives tomorrow evening.

Snowpack and Avalanche Discussion

The mountains near Bozeman, Big Sky and West Yellowstone have 1-2 feet of sugary, faceted snow on the ground which will struggle to support the weight of additional snow (see our videos from: Lionhead, Beehive, Saddle Peak, Buck Ridge). Yesterday Doug and I went to Taylor Fork to put up the weather station (photo). It was cold, windy and we found shallow, weak snow (video). Dave skied in Hyalite and found weak snow similar to elsewhere. Yesterday this snowpack was stable, but it won’t take much new snow to create an unstable slab on top (video).

This morning’s snow brings totals since Friday to 4-7” equal to 0.2-0.4” of snow water equivalent (SWE). This is a small amount of weight for the snowpack to hold, and today calm wind will not form fresh drifts. I do not expect many slab avalanches today, but wouldn’t be surprised to see a few. It is hard to know exactly how much weight the weak snowpack will hold, and slab avalanches might be possible with only a couple more inches of new snow.

Loose snow avalanches can be triggered on steep slopes, and can entrain the weak, sugary snowpack and become large and harmful (photo). Pay attention for small wind slabs in isolated areas near ridgelines. Cracks across the snow from your feet or skis are a sign the snow is unstable (photo). Before riding steep slopes, carefully evaluate the snowpack and consequences of an avalanche.

Today, new snow falling on a very weak snowpack creates elevated avalanche conditions and avalanche danger is rated MODERATE.

Near Cooke City the snowpack is 2-4 feet deep and generally stronger with less widespread weak layers than the rest of the advisory area. New snow since Friday totals 4” equal to 0.3” of SWE which will not overload the snowpack. We received a few reports of surface hoar buried 8-12” deep (photo), and sugary facets closer to the bottom of the snowpack on some slopes (video). It is worthwhile to dig and perform stability tests to search for these layers. We can’t completely rule out small wind slabs that formed with moderate wind yesterday, and dry loose avalanches in steeper terrain. Before traveling on steep slopes, carefully assess the snowpack and consequences of a slide. Today the avalanche danger is LOW.

If you get out, please send us your observations no matter how brief. You can submit them via our website, email (, phone (406-587-6984), or Instagram (#gnfacobs).

Upcoming Avalanche Education and Events

See our education calendar for an up to date list of all local classes. Here are a few select upcoming events and opportunities to check out:

Every Saturday in Cooke City, FREE snowpack update and rescue practice at the Round Lake Warming Hut between 10 a.m. and 3 p.m. Starts this Saturday, November 28. Poster with More Info.

Wednesday, December 16, 6-7 p.m., FREE online 1-hr Avalanche Awareness sponsored by Uphill Pursuits.

Monday, December 21, 6-7 p.m., FREE online 1-hr Avalanche Awareness sponsored by Mystery Ranch. Join HERE.

January 20 & 21 (plus field sessions the following weekends), Avalanche Fundamentals with Field Course. There are separate field sessions tailored for both skiers and splitboarders (Bridger Bowl) and snowmobilers (Buck Ridge). Register here.

The Last Word

Doug worked with Bruce Jamieson on a video about when, where and how to perform stability tests. Watch it here.