Good morning. This is Alex Marienthal with the Gallatin National Forest Avalanche Advisory issued on Friday, March 25, at 7:00 AM. Today’s advisory is sponsored by Grizzly Outfitters in partnership with the Friends of the Avalanche Center. This advisory does not apply to operating ski areas.
At 5 a.m. snowfall totals since yesterday morning range from 3” near West Yellowstone to 7” in Hyalite and 5-6” elsewhere. Winds have been out of the northwest at 10-20 mph with gusts in the 40s overnight. Temperatures are in the low teens F this morning and will be in the 20s F today. Wind will remain out of the northwest at 15-25 mph today, and then calm to 5-15 mph out of north-northeast tonight. The mountains will get 3-5” of snow today before high pressure sets in for the weekend.
Bridger Range Madison Range Gallatin Range
Lionhead area near West Yellowstone Cooke City
Since Tuesday, over a foot of snow fell on a variety of surfaces that range from melt-freeze crusts to dry powder or weak facets. We rode around Buck Ridge in the northern Madison Range on Wednesday (video), and skied near the Throne in the northern Bridger Range yesterday (video). In both areas the new snow was bonded well to the old snow surface, and any instabilities in the new snow are short-lived. During your travels, quickly dig 1-2 feet deep to assess the interface below the recent snow.
Wind slabs are the main avalanche problem today. Westerly winds have been steady and strong since Wednesday and formed wind slabs on many aspects. These slabs are on leeward slopes along most high-elevation ridgelines and on mid-elevation convex slopes and ridges. Slopes with cornices above likely have fresh wind slabs. The Big Sky ski patrol reported wind slabs were more stubborn to trigger yesterday than Wednesday, but not stubborn enough to ignore. Choose slopes sheltered from wind-loading, where dry powder remains untouched by wind. Avoid snow that appears wind affected or drifted into deeper denser slabs, especially if you see cracking or collapsing.
The southern mountains have a layer of weak facets buried 2-3 feet deep. Avalanches on this layer were observed near Cooke City over the past week (photo, photo, photo, photo), and Doug found this layer in the Taylor Fork on Sunday (video). Look for this layer on easterly and southerly aspects and assess it with a quick stability test in the top 2-3 feet of the snowpack, or avoid slopes that are suspect.
Recent snow and strong wind make avalanches possible today and the danger is MODERATE.
Eric will issue the next advisory tomorrow morning by 7:30 a.m. If you have any snowpack or avalanche observations to share, drop us a line at mtavalanche@gmail.com or leave a message at 587-6984.
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