Good Morning. This is Alex Marienthal with the Gallatin National Forest Avalanche Advisory issued on Saturday, February 24th at 7:00 a.m. Today’s advisory is sponsored by Gallatin County Search and Rescue and Spark R&D. This advisory does not apply to operating ski areas.
Since yesterday morning the mountains got a trace to 1” of low density snow. Temperatures this morning are single digits below and above zero F, and wind is west to southwest at 15-20 mph with gusts of 30-40 mph. Today, temperatures will be in the teens F with west-southwest wind at 20-30 mph. Snow showers through tonight will drop 1-2” in the mountains near Bozeman and Big Sky, and 3-5” near West Yellowstone and Cooke City. Another equal or greater amount of snow is expected Sunday night.
The mountains near Cooke City have twice the snow depth as the rest of our advisory area with 11 feet at the Fisher Creek SNOTEL station. Cornices are huge, recently wind loaded slopes have deep drifts, and a weak layer of facets buried 1.5-2’ deep is a concern. Eric found this weak layer on Tuesday and got unstable stability test results (video). This layer should be searched for and assessed before riding steep terrain.
Wind loaded slopes in steep rocky terrain or below ridgelines are most likely slopes to avalanche. Approach wind loaded slopes with caution, and stay a far distance back from large cornices and avoid slopes below. Recent heavy wind-loading and buried weak layers make human triggered avalanches possible today and the avalanche danger is rated MODERATE.
Over the past five days, the mountains throughout our advisory area had frigid temperatures with occasional, light precipitation totaling 2-3” of low density snow. The snowpack is generally strong without widespread weak layers, and avalanches today are small or difficult to trigger.
Strong winds yesterday had enough snow to drift into small wind slabs, which will grow larger today if there is more than a couple inches of new snow. Be cautious of these slabs, especially in terrain where consequences are high if caught in a slide. Wind earlier this week drifted snow into dense slabs on top of lower density snow, which Doug found at Bridger on Tuesday (video). These wind slabs could be triggered and should be avoided. They can be identified where a ski pole or hand punches through a harder slab into ‘hollow’ snow below.
Eric was at Hebgen Lake yesterday and found good overall stability. He identified features of concern during low danger, such as high consequence wind loaded slopes, and large cornices (video, photo). Be cautious of large cornices and slopes directly below, and isolated wind slabs near ridgelines and in steep, rocky terrain. Otherwise, avalanches are unlikely. Avalanche danger today is rated LOW.
If you get out and have any avalanche or snowpack observations to share, drop a line via our website, email (mtavalanche@gmail.com), phone (406-587-6984), or Instagram (#gnfacobs).
Upcoming Avalanche Education and Events
BOZEMAN
Feb. 28th, Know Before You Go avalanche awareness, 7:00 p.m. @ Procrastinator Theater, MSU
March 2nd and 3rd, SheJumps Companion Rescue Clinic, Info and Register HERE
March 2nd, Avalanche Awareness, 7-8:00 p.m., MAP Brewing Bozeman Split Fest
March 7th, Avalanche Awareness, 6-7:30 p.m. @ REI
DILLON
Feb. 24th and 25th, Snowmobile intro to avalanches w/ field course. More info: https://msuextension.org/conference/
COOKE CITY
Every Friday and Saturday, Current Conditions Update and Avalanche Rescue, Friday 6:30-7:30 p.m. at The Soda Butte Lodge in February. Saturday anytime between 10-2 @ Round Lake.
A good partner is essential for a safe day in the backcountry. This recent article from Backcountry Magazine provides some tips on how to find and be a safe backcountry partner.