GNFAC Avalanche Forecast for Sat Dec 7, 2019

Not the Current Forecast

This is Ian Hoyer with the Gallatin National Forest Avalanche Forecast on Saturday, December 7th at 7:00 a.m. Today’s forecast is sponsored by Cooke City Motorsports and Mystery Ranch. This forecast does not apply to operating ski areas.

Mountain Weather

There is no new snow this morning. Temperatures are mid-20s to low 30s F and winds are 20-30 mph out of the south and west with gusts as high as 50 mph. High temperatures today will be in the low to mid 30s F. Winds will remain moderate to strong out of the southwest. Snowfall will begin this afternoon with 8-10 inches by tomorrow morning near West Yellowstone and Cooke City and 1 to 3 inches near Bozeman and Big Sky.

Snowpack and Avalanche Discussion

Weak snow at the ground is widespread near Big Sky and West Yellowstone (photo). It remains possible to trigger an avalanche where these weak layers have a cohesive slab of newer snow above them. Any slope where you’re not sinking to the ground as you ski or ride deserves further investigation, as that is a good sign that you may have a cohesive enough slab for an avalanche (video, video, video). A quick Extended Column Test is a great way to check that slab-weak layer combination and search for signs of instability.

Avalanches are possible and the avalanche danger is MODERATE today.

Triggering avalanches on weak snow near the ground is also possible in the Bridger Range. However, these concerns are more localized to heavily wind loaded slopes near the ridgeline. On Tuesday and Thursday, Bridger Bowl Ski Patrol triggered large avalanches that broke on a thin layer of weak snow low in the snowpack (photo, video). Alex and Dave also found this weak layer and got unstable test results on it near the Throne earlier in the week (video). You can trigger similar slides today on high elevation slopes with thick drifts of windloaded snow. With these hard slabs, avoiding suspect slopes is your best strategy.

The avalanche danger is MODERATE on windloaded slopes. Elsewhere, the avalanche danger is LOW.

The Northern Gallatin Range and mountains around Cooke City have the deepest snowpacks and the most isolated weak layers. Triggering an avalanche is unlikely. However, we can’t rule out the possiblity that there may pockets with lingering instabilities. Dig a quick pit to look for unstable weak layers before committing to a steep slope. The avalanche danger is LOW.

If you get out, please send us your observations no matter how brief. You can fill out an observation form, email us (, leave a VM at 406-587-6984, or Instagram (#gnfacobs).

Backcountry Barriers Contest

Click here to learn more about the Backcountry Barriers Contest:

We recognize that backcountry skiing can be daunting. That’s why Ben Goertzen and the Friends of the Gallatin National Forest Avalanche Center have teamed up to help breakdown some of the most prominent barriers of entry to backcountry skiing through this campaign. One lucky winner will be given a complete backcountry skiing kit, a spot in an avalanche awareness course, and featured in a three part video series that ends with an excursion into the backcountry with professional skier and filmmaker, Ben Goertzen. These videos will be used by the Friends of GNFAC to help other aspiring backcountry skiers gain awareness, knowledge and start to breakdown their barriers to entry.

Upcoming Avalanche Education and Events

Our education calendar is full of awareness lectures and field courses. Check it out and plan to attend one or two: Events and Education Calendar.


December 11, 1-hr Avalanche Awareness, 6-7 p.m. at REI.

December 12, Avalanche Awareness + Beacon Practice, 6-8 p.m. at Story Mill Community Center.


9 & 10 December, Snowmobile/Ski Introduction to Avalanche w/ Field Course, 12-5p Dec 9 and field day Dec 10. More info and Register Here.


December 9, 1-hr Avalanche Awareness, 7-8 p.m. at Manhattan High School.


Every Friday and Saturday, Snowpack Update and Rescue Training. Friday, 6:30-7:30 p.m. at the Soda Butte Lodge. Saturday anytime between 10-2 @ Round Lake.

The Last Word

The Gallatin Valley Snowmobile Association deserves a shout-out for putting up new beacon checkers at Taylor Fork and Buck Ridge Trailheads.

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