GNFAC Avalanche Advisory for Sat Jan 13, 2018

Not the Current Advisory

Good Morning. This is Alex Marienthal with the Gallatin National Forest Avalanche Advisory issued on Saturday, January 13th at 7:00 a.m. Today’s advisory is sponsored by Yellowstone Arctic Yamaha and Yamaha Motor Corp and The Friends of the Avalanche Center. This advisory does not apply to operating ski areas.

Mountain Weather

Since yesterday morning the Bridger Range got 12” of new snow, the mountains near Cooke City, Big Sky and Hyalite got 3-4” with 1” near West Yellowstone. Wind overnight was westerly at 15-25 mph with gusts of 30-40 mph. Temperatures this morning are high teens to mid-20s F and will be mid to high 20s F today. Wind will be west-northwest at 20-30 mph. Snowfall will continue this morning with another 1-3” possible.

Snowpack and Avalanche Discussion

The Bridger Range has a foot of new snow equal to 1.4” of snow water equivalent (SWE) since yesterday morning, and 2.5 feet of snow equal to 3” of SWE since Wednesday morning. Eric and I were in the northern Bridgers yesterday and found an overall strong snowpack with new snow instabilities our main concern (video). The rapid, heavy load of snow since yesterday will increase the size and likelihood of avalanches today. Moderate wind overnight drifted new snow into slabs near ridgelines that will be easy to trigger or break naturally. Despite a fairly strong snowpack, the heavy cumulative load since Wednesday makes avalanches breaking on facets buried 3-4’ deep more likely. Avoid wind loaded slopes and be extra cautious of all steep terrain today. The avalanche danger is HIGH on wind loaded slopes and CONSIDERABLE on non-wind loaded slopes.

The Lionhead area near West Yellowstone has an unstable snowpack, and 2 feet of snow this week equal to 2.4” of snow water equivalent (SWE) created very dangerous avalanche conditions (video, photo). Yesterday’s avalanche warning is no longer in effect, but large avalanches are easy to trigger and can be triggered from flat or low angle terrain below steep slopes. Avoid travel on and underneath steep slopes. Today, large avalanches are easy to trigger and natural avalanches are possible. The avalanche danger is CONSIDERABLE.

The southern Madison and Gallatin Ranges and mountains near Cooke City got to 2-2.5 feet of snow equal to 2-2.5” of SWE since Wednesday. The snowpack in these areas is handling this load well, as Doug found in Bacon Rind on Thursday (video). However, more snow equals more avalanches, and this recent snow was no exception. Yesterday, a large natural avalanche was observed on the Fin near Cooke City (photo), and skiers reported collapsing on lower elevation terrain. A layer of facets buried 2-4’ deep is stronger than it was a few weeks ago, but avalanches on this layer are easier to trigger with the weight of the recent snow. New snow, wind and natural avalanches mean avalanches are easy to trigger, and the avalanche danger today is CONSIDERABLE.

The mountains near Hyalite and Big Sky have had less snow than elsewhere, and have a generally stronger snowpack. Moderate westerly winds drifted recent new snow into wind slabs that are easy to trigger near ridgelines today. There’s still the possibility for slides to break on facets buried 2-4’ deep. Skiers in Dudley Creek in the northern Madison Range remotely triggered a large avalanche yesterday (photo). This instability is confined to specific terrain (where the snowpack is relatively shallow, 3-5’ deep), and needs to be watched for when traveling on mid to low elevation slopes or areas where the snowpack depth is highly variable. Today, the avalanche danger is rated CONSIDERABLE on wind loaded slopes and MODERATE on non-wind loaded slopes.

If you get out and have any avalanche or snowpack observations to share, drop a line via our website, email (, phone (406-587-6984), or Instagram (#gnfacobs).

King and Queen of the Ridge

King and Queen of the Ridge, Saturday, February 3rd. A Hike and Ski/Ride-a-Thon fundraising event to support the Friends of the Gallatin National Forest Avalanche Center. Sign up and start collecting pledges HERE.

Upcoming Avalanche Education and Events

Events and Education Calendar


Jan. 15, Avalanche Awareness, 6-7 p.m. at Yellowstone Motorsports

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

Jan. 22, MAP Brewing Pint Night, 4-8 p.m. MAP donates 50 cents of every pint sold to the Friends of the Avalanche Center.

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


Jan. 20, Avalanche Awareness, 7-8 p.m. at West Yellowstone Holiday Inn Conference Center


Today!!!, Rescue Clinic, 10 a.m. at Homestake Lodge


Jan. 16, Avalanche Awareness, 6:30-8 p.m. at U.M. Western Library


Every Friday and Saturday, Current Conditions Update and Avalanche Rescue, Friday 6:30-7:30 p.m. at The Antler's Lodge in January. Saturday anytime between 10-2 @ Round Lake.

The Last Word

Watch the new Dashboard Talks, Episode 3: Down in a Hole. You should dig snowpits and perform stability tests, but how many is enough? Well that depends... Doug and Eric discuss the relationship between your objectives and pit digging.