Good morning. This is Alex Marienthal with the Gallatin National Forest Avalanche Forecast on Saturday, February 18th at 7:00 a.m. This information is sponsored by Gallatin County Sheriff Search and Rescue and Grizzly Outfitters. This forecast does not apply to operating ski areas.
This morning there is no new snow. Temperatures are single digits to teens F. Wind is southwest-west at 10-25 mph with gusts of 30-45 mph. Today temperatures will reach 20s F with westerly wind at 15-30 mph. Snow showers are expected to deliver 2-5” by this evening, and by tomorrow morning a total of 8-15” are possible in the Bridger Range and Hyalite with 4-8” elsewhere. More heavy snowfall is possible through at least the first half of the week.
Today a person can trigger avalanches that break in recently formed drifts of snow, or fresh drifts that form as snow falls later today. Over the last three days, wind out of the north and west drifted recent new snow into thicker slabs which might avalanche under the weight of a person. Two days ago, riders north of Cooke City saw a recent snowmobile triggered slide on Crown Butte (details), and skiers triggered a small slide in a wind drift in Bradley’s meadow north of Bridger Bowl (details). There were also slides earlier this week on Mt. Blackmore, in Twin Falls Basin, on Buck Ridge, and in Beehive. Although stability has gradually improved, recent avalanche activity is a sign to remain cautious of wind-loaded slopes for at least another day. Any new snow today will be drifted into fresh slabs that may be small, but easy to trigger. Before riding steep slopes, carefully evaluate the stability of recently formed drifts, and have a flexible plan in case you find fresh, unstable wind slabs that form today.
Recent avalanche activity appears to have broken in the recent new snow, but there are also buried weak layers in the top 3 feet of the snowpack. Avalanches on these layers are currently unlikely, but it is worthwhile to dig to assess these weak layers before riding steep slopes (Buck Ridge video, Bacon Rind video). Avalanche danger is MODERATE on wind-loaded slopes and LOW on non-wind loaded slopes.
The Lionhead area near West Yellowstone received less snow over the last couple weeks and avalanches are unlikely today. Yesterday Ian and I rode near Lionhead Ridge and saw one previously reported small, rider triggered avalanche from a few days ago (photo). Recently formed drifts appeared to be small, not widespread and are unlikely to be triggered after having time to stabilize since they formed. Additionally, buried weak layers have become unreactive and unlikely to cause deeper avalanches. There is always some uncertainty when we generalize the snowpack over a large area, so if you choose to ride steep slopes it is worthwhile to assess the snowpack for wind-loading and buried weak layers, and always critical to follow safe travel protocols of only allowing one person at a time on or below steep slopes and carrying proper avalanche rescue gear (Lionhead video). Today avalanches are unlikely and avalanche danger is LOW.
Expect avalanche danger to rise overnight and tomorrow. If heavy snowfall begins early today, fresh unstable drifts may form and cause danger to increase by this evening.
Please share avalanche, snowpack or weather observations via our website, email (mtavalanche@gmail.com), 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.
February 19, 10 a.m.-2p.m. Companion Rescue Clinic Field Day in the Bozeman area. Required Online Classroom Session at 6 p.m. on Feb 18. Information and course registration are HERE.
March 3-5, Bozeman Splitfest. More info and register here.
Every Saturday, 10 a.m. - 2:00 p.m. Avalanche Rescue Training, drop in for any amount of time. Round Lake Warming Hut, Cooke City. Free.
Loss in the Outdoors, is a support group for those who have been affected by grief and loss related to outdoor pursuits. Check out the link for more information.
Bruce Jamieson’s videos on Snow Science explain heady topics to the layman. Understanding the avalanche dragon helps keep us alive.