Good morning. This is Alex Marienthal with the Gallatin National Forest Avalanche Advisory issued on Thursday, March 24, at 7:00 AM. Today’s advisory is sponsored by Soda Butte Lodge and Bountiful Table. This advisory does not apply to operating ski areas.
Scattered snow showers yesterday delivered a trace to 2” of low density snow to the mountains. Temperatures this morning are in the teens F and will be in the 20s F today. Winds overnight were out of the west-southwest at 10-20 mph with gusts in the mid-30s and up to 45 mph at Bridger Bowl. Strong westerly winds will continue today and increase to 25-35 mph this afternoon and shift to the north overnight. Expect snow late this morning through tomorrow. The mountains will get 5-7” by morning and another 3-5” tomorrow.
Bridger Range Madison Range Gallatin Range
Lionhead area near West Yellowstone Cooke City
The main concerns today are avalanches that involve new snow from the last 48 hours. Since Tuesday the northern mountains received 7-12” of snow that totaled .8” of snow water equivalent (SWE), and the southern mountains got 4-6” of snow that totaled around .5” of SWE. Yesterday, Doug and I rode from Buck Ridge to Cedar Mountain in the northern Madison Range. We saw a couple small avalanches and had unstable test results all within the new snow (video). The Big Sky ski patrol reported storm slabs and wind slabs that were sensitive to ski cuts and explosives on all aspects yesterday. The recent snow fell on a variety of snow surfaces that range from crusts on sunny slopes to dry powder or weak facets on colder, shadier slopes. Dig 1-2 feet deep to quickly assess the interface below the recent snow.
Westerly winds increased overnight to usher in the next storm today. Expect to find sensitive wind slabs near ridgelines and on convex leeward slopes. Strong wind will persist today and heavy snowfall may begin this afternoon. Fresh slabs will increase in size through the day. Avoid steep wind-loaded slopes, especially where you find cracking or deeper drifted snow.
Avalanches on buried persistent weak layers, though less likely, are an additional concern in some areas. The southern mountains have a layer of weak facets buried 2-3 feet deep, which is mostly found on easterly through southerly aspects. Avalanches that likely failed on this layer were observed near Cooke City yesterday (photo) and last weekend (photo, photo, photo). Doug also found this layer in the Taylor Fork on Sunday (video). In the northern mountains, weak facets were observed on cold and shady slopes prior to the last storm. Assess these layers with a quick stability test in the top 2-3 feet of the snowpack, or avoid steep slopes that are suspect.
Today, avalanches are possible and the danger is MODERATE. Strong wind will continue today and the danger could rise to CONSIDERABLE this afternoon if heavy snowfall begins early.
I 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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