Good morning. This is Alex Marienthal with the Gallatin National Forest Avalanche Advisory issued on Friday, March 4, at 7:00 AM. Today’s advisory is sponsored by Mountain Valley Motorsports of Cody and World Boards. This advisory does not apply to operating ski areas.
The mountains near Bozeman and Cooke City got around 2” of snow since yesterday, while the rest of the area remained dry. Winds have been westerly at 15-20 mph with gusts near 40 mph. Temperatures this morning are in the high teens to low 20s F and will be in the high 30s F today. Wind will be light today, around 5-15 mph out of the west-southwest, and skies will be mostly clear. The next chance for snowfall is Sunday.
Southern Madison Range Southern Gallatin Range
Lionhead area near West Yellowstone Cooke City
The mountains in the southern half of our advisory area have a layer of buried surface hoar that continues to be unstable. This layer is buried 1-3 feet deep and can be identified as a stripe in the snowpit wall (photo). Doug got unstable test results on this layer on Wednesday at Bacon Rind, in the same spot that Eric, Karl, and I had stable results one week ago (video, photo). The mountains have received enough snow in the past week to keep this layer unstable. Avoid steep slopes where it exists. It does not exist on every slope. If you don’t find it, dig another pit to make sure it is not there. The slide triggered by a snowmobiler last week in cabin creek is an example that these avalanches can be deep and dangerous, even on small slopes (photo). In addition, strong westerly winds this week formed wind slabs that will remain possible to trigger today.
It has become unlikely to trigger an avalanche on buried facets or depth hoar. However, these weak layers exist on many slopes and could produce an avalanche in isolated areas or extreme terrain.
It will be possible to trigger a wind slab or an avalanche on buried surface hoar today, so the avalanche danger is MODERATE.
Bridger Range Northern Madison Range Northern Gallatin Range
The mountains near Bozeman and Big Sky had a series of small storms this week that improved the riding without decreasing stability. Although some slopes have weak snow and a poor snowpack structure, a relatively stable snowpack exists due to minimal stress from recent light snowfall. This snow was high density and bonded well to the old snow surface. Strong winds may have blown this snow into wind slabs that are most likely found on steep alpine slopes near ridgelines (video).
Today, the avalanche danger is rated LOW. Avalanches are unlikely, but not impossible. Consider the consequences of terrain and watch out for slopes with isolated wind slabs or pockets of unstable snow. It is a good idea to dig a pit before committing to a slope to be sure the snowpack is what you expect. Multiple observers have reported changing their objectives during low danger, after digging a pit and finding unstable test results.
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.
EVENTS and AVALANCHE EDUCATION
A complete calendar of classes can be found HERE.
Bozeman: Wednesday, March 9, 6-7 p.m. 1-hr Avalanche Awareness, REI.