GNFAC Avalanche Forecast for Mon Sep 18, 2017

Not the Current Forecast

Good Afternoon. This is Alex Marienthal with pre-season avalanche, weather, and event information for the Gallatin National Forest Avalanche Center on Monday, September 18th. This bulletin is sponsored by Grizzly Outfitters, our title sponsor for the Powder Blast event on October 27th, 2017.

Mountain Weather

This weekend welcomed a change to cold, wet weather. Brackett Creek SNOTEL in the Bridger Range recorded 3” of precipitation over 48 hours, which totaled 2.5 feet of snow at high elevations (Outside our advisory area, the Tobacco Roots had similar snowfall). The mountains near Big Sky, West Yellowstone, Cooke City, and the Hyalite area got around a foot of dense snow.

The immediate forecast holds a good outlook for more snow, but October weather will determine if these are the first layers of our winter snowpack. As a cold front passes this afternoon wind speeds could gust 40-60 mph, and the mountains above 5500 feet are expected to get 3-5” of snow Tuesday morning. Valley rain and mountain snow are forecast periodically through Saturday morning. Sunday may host dry weather, with a possible return to cool and wet weather next week.

Snowpack and Avalanche Discussion

Snow in town Saturday morning was a generous reminder to dig out the snow tires, gather firewood, and prepare ski gear. Many folks took advantage of 1-2 feet of dense new snow in the mountains, and we heard about great skiing as well as signs of instability and avalanches.

If there is snow on the ground it is time to think about and prepare for avalanches. Here are some things to consider as we dust the cobwebs off our winter toolbox.

  • Everyone in your group should always carry a beacon, shovel, and probe. Put fresh batteries in your beacon, check your probe and shovel for damage, and know how to use them.
  • Travel one at a time in avalanche terrain, whether climbing or descending.
  • Be extra cautious of slopes where wind has deposited deep drifts of snow, or if you witness collapsing or cracking of the snow.
  • With minimal snow cover, the best skiing is found where snow is drifted deep. Find terrain less steep than ~32 degrees if you are unsure of stability.
  • Small slides can have high consequences when the snow cover is thin. Traumatic injury is more likely than burial, and can be serious or life-threatening in the backcountry.
  • Hunters are exposed to avalanche terrain, and often travel alone without avalanche rescue gear. Hunters should avoid travel on or below steep (>32 degrees), snow covered slopes.
  • Small slopes can slide and bury a person in confined terrain like road cuts, gullies, and creek beds. Avoid terrain traps like these where snow is deep or drifted.                                         

Avalanches have caught and injured skiers, hunters, and climbers during the early-season. Travel and prepare for avalanches like you would in the middle of winter.


We are getting prepared for winter, scheduling avalanche classes, and setting up weather stations. Drop a line if you get out in the hills and have any avalanche or snow observations to share, e-mail mtavalanche@gmail.com or call 406-587-6984.

Powder Blast Fund-raiser

27 October, 6:30 p.m. at The Emerson Cultural Center. Tickets and Info

Grizzly Outfitters of Big Sky is title sponsor of this year's 19th Annual Powder Blast. Mystery Ranch, World Boards, Community Food Co-op and Spark R&D, are our other key supporters. Join us for the best fundraiser of the year! All proceeds benefit the Friends of the Avalanche Center which supports avalanche awareness, education and information throughout southwest Montana.

Your $30 donation gets you an unforgettable evening at the Emerson Cultural Center.

Beer from Katabatic Brewing Company; Wine from Montana Ale Works; Dinner by Bountiful Table; Music by DJ Missy O'Malley

And the best silent auction of outdoor gear in the valley!


Events and Education Calendar - Stay tuned as we will update our calendar with more classes over the next few months.

11 October, MSU Snow and Avalanche Workshop, 5-9 p.m. at M.S.U. Free event! Info Here

1 November, Avalanche Awareness, 6-7:30 p.m. at REI Bozeman

6 December, Avalanche Awareness, 6-7:30 p.m. at REI Bozeman

7 December, Avalanche Awareness and Beacon Practice, 6-8 p.m. at Beall Park, Bozeman

Nov. 29, 30 and Dec. 2 or 3, Introduction to Avalanches w/ Field Day, Info and Register Here

Jan. 12 and 13, Companion Rescue Clinic, Info and Register

Jan. 17, 18 and 20 or 21, Introduction to Avalanches w/ Field Day, Info and Register Here

Jan. 24, 25 and 27, Advanced Avalanche Workshop w. Field Day, Info and Register Here

Feb. 9 and 10, Companion Rescue Clinic, Info and Register

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