GNFAC Avalanche Forecast for Wed Dec 13, 2023

Not the Current Forecast

Good morning. This is Doug Chabot with the Gallatin National Forest Avalanche Forecast on Wednesday, December 13th at 6:45 a.m. This information is sponsored by Montana State Parks and Bridger Bowl. This forecast does not apply to operating ski areas.

Bridger Bowl is closed to all uphill traffic. Ski patrol is doing avalanche mitigation in anticipation of opening this Friday, December 15.

Mountain Weather

Under clear skies there is no new snow to report. Wind is 10-15 mph with gusts of 25 mph out of the W-S and E. Ridgetop temperatures are in the low to mid 20s F, but an inversion has lower elevations 5-10 F cooler. Today will be sunny, the wind will remain the same and temperatures will climb into the upper 20s. The next 7 days are forecasted to be warm and sunny, a metaphorical lump of coal in the stocking of sledders, skiers and boarders.

Snowpack and Avalanche Discussion

All Regions

The snowpack is unstable. Yesterday, a skier on Mt. Blackmore, in the northern Gallatin Range, triggered the SE face as he skied. Luckily he was not caught, and fortunately he shared a picture and POV video. This avalanche is instructive because the unstable conditions they found could be anywhere in our forecast area, such as Saddle Peak, Beehive Basin or Cooke City. Ian and I skied in a backcountry snowpack at Bridger Bowl yesterday. We got a loud collapse in the Fingers Meadow, stopped, and dug in 2 feet of snow. We found weak grains of sugary facets and depth hoar at the base of the snowpack. The collapse was Mother Nature shouting the snow is unstable. Being snow nerds we dug, and we were unable to isolate a column because it kept breaking (pic, snowpit and video). Furthermore, sledders got collapses (whumpfs) in Lionhead during an avalanche course yesterday and skiers had large whumpfs in Cooke City 2 days ago, evidence of similar snow structure.

The snowpack will be slow to heal. A persistent weak layer of facets and depth hoar can take months to strengthen. This layer is also protected from our skis chewing it up on popular runs because we float above it, which snow scientist Karl Birkeland shows us in a recent video.

Stay out of avalanche terrain today. This is our first day in the last 12 when there has been no new snow in our forecast area. The avalanche danger will slowly come down, but not yet. Triggering a slide like the one on Blackmore is just as likely today as it was yesterday. 

Throughout our forecast area, the avalanche danger is rated CONSIDERABLE on all slopes.

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 (, 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.

TOMORROW, Thursday, December 14th, 6:30 p.m., Community Partnership Series @ MAP Brewing, featuring “RUN” with Wiley Miller, and Q&A with GNFAC forecaster Alex Marienthal.

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.

The Last Word

Watch this video from Dr. Karl Birkeland (former director of the National Avalanche Center, now retired with more time to do large stability tests) performing a Rutschblock Test and showing how easy it is for a person to trigger an avalanche on our current snowpack.

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