GNFAC Avalanche Forecast for Mon Oct 21, 2019

Not the Current Forecast

This is Ian Hoyer with pre-season avalanche, weather and event information for the Gallatin National Forest Avalanche Center on Monday, October 21st. This information is sponsored by Highline Partners and Uphill Pursuits, both supporters of Friday’s Powder Blast fundraiser.

Mountain Weather

Since Thursday evening, 7-9” of snow fell around Cooke City and West Yellowstone. The mountains near Big Sky and Bozeman received 13-19”.  Ridgetop winds averaged 15-25 mph out of the west. Mountain temperatures generally remained below freezing with lower elevation temps reaching the low 30’s. Intermittent snowfall will continue through Wednesday, with another 6” to a foot of snow possible, favoring the northern mountains. Sunny skies and warmer temperatures return towards the end of the week.

We will update our Weather Log and Regional Conditions every morning with snowfall totals, and our Avalanche Activity list if we get a report.

Snowpack and Avalanche Discussion

All Regions

The mountains have seen a big change in the last four days. Slopes that were bare last week are now covered by up to 18” of new snow. On these recently bare slopes, avoiding rocks and stumps hiding just under the surface is the number one concern. Slopes that held snow before this weekend will make for easier travel on skis, but also have the most potential to avalanche (photo). This older snow is generally present above about 8000’ feet, particularly in wind drifted areas and on shadier aspects.

Yesterday, ice climbers in Hyalite triggered a small slide as they approached a climb (photo). While this slide was small, getting swept off your feet could have disastrous consequences will all the rocks still exposed this time of year and bigger avalanches are also possible.

Any slope with old snow is suspect. The only way to know whether it’s there is to dig down to look for it. If you find the old snow, take a minute to do a quick Extended Column Test. Watch this video to remind yourself how to do one. You’ll spend longer watching the video than it’ll take to do the test. Also keep your eye out for thicker wind drifts and stay alert for signs of instability such as recent avalanche activity, cracking or collapsing of the snowpack. Any of these signs are a clear warning to avoid steep slopes.

Hunters, ice climbers, and skiers have all been caught in early season avalanches (accident reports). Regardless of activity, the same advice applies: either avoid avalanche terrain (>30 degree snow covered slopes) entirely or bring a partner, travel one at a time, carry the standard rescue gear (beacon, shovel, and probe) and carefully assess the snowpack.

We are preparing for winter, setting up weather stations and beginning to collect snowpack information. If you have avalanche, snowpack or weather observations to share, please submit them via our website, 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 and plan to attend one or two: Events and Education Calendar.

Get tickets for the 21st Annual Powder Blast Fundraiser on October 25th at The Emerson Ballroom. New this year is an online list of auction items, take a look at all the great stuff that will be available! 


6 November, 1-hr Avalanche Awareness, 6-7pm @ REI Bozeman.

7 November, 1-hr Avalanche Awareness, 6-7pm @ Langford Hall, MSU.

12 November, 1-hr Avalanche Awareness, 6-7pm @ Montana Ski Tuning and Boot Fitters.

14 November, 1-hr Avalanche Awareness, 6-7pm @ South Hedges Hall, MSU.

14 November, 1-hr Avalanche Awareness, 6-7pm @ Uphill Pursuits.

20 November, 1-hr Avalanche Awareness, 6-7pm @ The Mountain Project.

4 & 5 December, Introduction to Avalanche w/ Field Course, Evenings of December 4 & 5 plus one field day either December 7, 8 or 14. Snowmobile specific field day offered December 14. More info and Register Here.


6 November, 1-hr Avalanche Awareness, 6-7pm @ The Base Camp in Helena.


19 November, 1-hr Avalanche Awareness, 6-7pm @ The Base Camp in Billings.

The Last Word

Get tickets for the 21st Annual Powder Blast Fundraiser on October 25th at The Emerson Ballroom.

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