GNFAC Avalanche Forecast for Sat Jan 4, 2020

Not the Current Forecast

Good Morning. This is Ian Hoyer with the Gallatin National Forest Avalanche Forecast on January 4th at 7:00 a.m. Today’s forecast is sponsored by Your Montana Chevy Dealers and Highline Partners. This forecast does not apply to operating ski areas.

Mountain Weather

Three inches of new snow fell yesterday morning in Cooke City. Less than an inch fell elsewhere across the advisory area. Winds are 20-30 mph out of the south and west, with gusts into the 40s and 50s mph near Bozeman and Big Sky. Winds are lighter near Cooke City and West Yellowstone, at 10-20 mph. Temperatures vary widely this morning, from the high teens to low 30s F. Temps will rise into the high 20s and mid-30s F today. Winds will be 20-30 mph out of the southwest, with gusts up to 40 mph. Snowfall this afternoon will bring 1-3 inches by tomorrow morning.

Snowpack and Avalanche Discussion

All Regions

The combination of heavy snowfall earlier this week (1-2 ft with 1-1.7” of snow water equivalent), strong winds, and weak layers in the snowpack have created dangerous avalanche conditions. Avalanches can break beneath the new snow (1-2 ft deep), in a wind drift (3-4 ft deep), or on weak layers near the ground. Numerous natural and human triggered avalanches have been reported in the Bridger Range, near Big Sky, and near Cooke City (avalanche log). Snowfall totals, the amount of wind drifting, and the distribution of weak layers varies a bit between the different mountain ranges, but from a practical perspective it makes no difference. Triggering a large avalanche is likely on any steep slope.

Yesterday, Alex went to the Throne in the northern Bridger Range and found just about every red flag of avalanche danger. He saw a large natural avalanche on Saddle Peak while driving up the highway, had the snowpack collapse under him, got unstable test results, and had strong winds quickly drifting snow over his tracks (video). He heeded these signs and stuck to slopes less than 30 degrees.

Last weekend, skiers in the Tobacco Root Mountains (outside our advisory area) remotely triggered an avalanche that broke 6 ft deep on the adjacent face while they were on a lower angled ridgeline (photo). They had dug three snowpits during their ascent of the ridgeline with no signs of instability. Their first indication of unstable snow was triggering this huge slide. There is no need for complicated snowpack assessments today. There has been lots of new snow (video). There are thick fresh wind drifts (video). And on some slopes this is all stacked onto unstable weak layers (video). Avoid steep slopes to avoid triggering a large avalanche. Human triggered avalanches are likely and the avalanche danger is CONSIDERABLE.

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).

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.


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.


TONIGHT! January 4, 1-hr Avalanche Awareness, 7-8 p.m. at West Yellowstone Holiday Inn.

January 25, 1-hr Avalanche Awareness, 7-8 p.m. at West Yellowstone Holiday Inn.


January 7, Women's Specific Avalanche Awareness + Beacons, 6-8 p.m. at Story Mill.

January 8, 1-hr Avalanche Awareness, 6-7 p.m. at REI.

January 8, 1-hr Avalanche Awareness, Gallatin Valley Snowmobile Association Groomer Building.

January 10 & 11, Companion Rescue Clinic, 6-8 p.m. on the 10th at REI and 10-2 p.m. on the 11th at History Rock. More info and Register Here.

January 15 and 16, Introduction to Avalanche w/ Field Course, evenings of January 15 & 16 plus one field day either January 18, 19 or 25. Snowmobile specific field day offered January 25. More info and Register Here.

The Last Word

On New Year’s Day, two snowmobilers lost their lives in an avalanche near Seeley Lake, northeast of Missoula. Our condolences go out to their friends and families. The West Central Montana Avalanche Center has released a preliminary report.

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