Good morning. This is Alex Marienthal with the Gallatin National Forest Avalanche Forecast on Monday, January 8th at 7:00 a.m. This information is sponsored by Basecamp Gallatin and Yamaha and Alpine Yamaha in Livingston. This forecast does not apply to operating ski areas.
Yesterday the Bridger Range got 6-7” of low density snow with 1-3” elsewhere. Wind has been northwest-west at 5-15 mph with gusts to 20 mph, and overnight at Lionhead the wind increased to 20 mph with gusts to 35 mph for a few hours. Temperatures are single digits to low teens F this morning. Today, under mostly clear skies, temperatures will reach mid-teens F and wind will increase to 10-25 mph from the west-northwest. The next round of snow should arrive overnight with 1-2” possible by early morning and 3-5” possible through tomorrow.
Snowfall totals since Friday are 4-9” of low density snow (0.3-0.5” snow water equivalent), and Ian and Dave found up to 16” (0.7” SWE) in the Centennials near Island Park yesterday (video, observation). Overall not the most impressive multiple day storm totals, but enough to improve general travel, riding and skiing conditions, and enough to increase avalanche danger.
Winds have been calm to light and our observations from yesterday note the low density snow has not posed a major hazard, but that will change today. Winds will increase enough to drift the recent snow into stiffer slabs. These slabs will easily avalanche under the weight of a person because they sit on a very weak snowpack that exists on most slopes throughout our advisory area (snowpack near I.P. photo, Buck Ridge snowpack photo). I saw this weak snowpack the last couple days near Big Sky and in the Bridgers (video), and on Saturday at Buck Ridge just a couple inches of snow and a few hours of wind were enough to create widespread avalanche activity (video, photos and observation).
On slopes without wind loading the weak snowpack is capable of producing large dry loose avalanches on long, sustained steep slopes (photo from Buck Ridge, photo from Beehive, photo from Cooke). These ”facet sloughs” can be started by a skier or rider pushing on the slope, or from a small wind slab or loose avalanche of new snow from above. They carry plenty of force to knock you over as they entrain almost the entire snowpack. On Saturday we saw a few of these dry loose slides and easily triggered a few fresh wind slabs (video, wind slab photos).
Watch for signs of recent wind-loading such as cornices, rounded smooth pillows of snow and snow surfaces with wavy textures. Cracking across the surface of the snowpack is a sign you have found an unstable drift that will slide on steep slopes. Because of the very weak snowpack, avalanches may break above you, or wider or larger than expected. Any size slide can get you into trouble if it carries you into trees, over cliffs or rocks, or piles up deeper in a confined gully. If you have any doubts, choose routes that avoid slopes steeper than 30 degrees and the runout zones below. Today the avalanche danger is CONSIDERABLE on wind-loaded slopes and MODERATE on non-wind-loaded slopes throughout the forecast area.
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 (firstname.lastname@example.org), 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.
Every weekend in Cooke City: Friday at The Antlers at 7 p.m., Free Avalanche Awareness and Current Conditions talk, and Saturday from 10 a.m.-2 p.m. at Round Lake Warming Hut, Free Rescue Practice.
King & Queen 2024, 3 February 2024. Form a team or sign up individually to hike laps on the Bridger Bowl ridge to fundraise for the Friends of the Avalanche Center.
Loss in the Outdoors is a support group for those affected by loss and grief related to outdoor pursuits. Check out the link for more information.
Here’s a quick read, The Invisible Hands of Avalanche Work, an interview with GNFAC forecaster, Doug Chabot.