Good Morning. This is Alex Marienthal with the Gallatin National Forest Avalanche Advisory issued on Monday, February 13th at 7:00 a.m. Today’s advisory is sponsored by Yellowstone Club Community Foundation and Montana State Parks. This advisory does not apply to operating ski areas.
No snow fell in the mountains over the last 24 hours. Temperatures this morning are high teens to 20s F and wind is northwest to west at 10-20 mph with gusts in the 30s. Today will be sunny with temperatures in the 20s to low 30s F and wind from the northwest to north at 10-15 mph. The next couple days are clear with a slight warming trend and a wet weekend ahead.
Cooke City
An historic avalanche cycle took place in Cooke City after 8-10 feet of snow and strong winds last week. When skies cleared this weekend huge avalanches were visible, which ran historic distances, broke large trees, and deposited 20’ deep debris piles. Doug toured the carnage yesterday and posted a couple dozen photos and made a video to summarize the activity. See our photo page for a thorough tour of the aftermath.
The snowpack is adjusting to last week’s massive load, but very large slabs could be triggered today. Avoid steep, wind loaded slopes and their runout zones, and be extra cautious near all avalanche terrain. Avalanche danger today is CONSIDERABLE.
Madison Range Gallatin Range Lionhead area near West Yellowstone
The mountains near Big Sky, West Yellowstone, and south of Bozeman received a small fraction of the snow that fell near Cooke City last week. However, they got enough to make buried weak layers unstable. Over the weekend skiers and riders experienced collapsing, and reported unstable test results on facets buried 1.5 to 2 feet deep in Hyalite, Beehive (video, photo), and the southern Madison Range (video). A snowmobiler was partially buried in a slide on a heavily wind loaded slope in the Taylor Fork yesterday, and a rider triggered a slide Saturday on Buck Ridge (photos). Large natural avalanches were observed on wind loaded slopes north of Big Sky (photo), Hyalite (photo), and Tepee Basin (photo).
Avalanches are most likely on wind loaded slopes and buried weak layers make avalanches possible on other steep slopes. Weak layers are found on some slopes and absent on others. Look for and assess these layers if riding in steep terrain, and dig a hole or two on each aspect you plan to travel on. Avalanche danger today is CONSIDERABLE on wind loaded slopes and MODERATE on non-wind loaded slopes.
Bridger Range
In the Bridger Range small wind slabs are possible to trigger and are found near ridgelines and on convex terrain. Yesterday skiers triggered a small wind slab on Saddle Peak, on a convex rollover below the large cliffs. Steep slopes with wind affected snow should be approached with caution or avoided, especially above cliffs and terrain traps.
Weak snow at the base of the snowpack in the Bridger Range is generally stable due to minimal recent stress from snow and wind-loading (video). Avalanches on this layer are unlikely, but worth watching out for. Dig to assess this weak layer and be cautious where it lies below wind slabs. Avalanche danger today is MODERATE on wind loaded slopes and LOW on non-wind loaded slopes.
Doug will issue the next advisory tomorrow morning by 7:30 a.m.
Nearby Incident: On Friday, a snowmobiler triggered a slide north of Lincoln, MT (not within any advisory area). He deployed his airbag and was not caught while his sled was partially buried. A short report and photos of the incident here.
We rely on your field observations. Send us an email with simple weather and snowpack information along the lines of what you might share with your friends: How much new snow? Was the skiing/riding any good? Did you see any avalanches or signs of instability? Was snow blowing at the ridgelines? If you have snowpit or test data we'll take that too, but this core info is super helpful! Email us at mtavalanche@gmail.com or leave a message at 406-587-6984.
Beacon Training Park at Beall: Open and free to the public for avalanche beacon practice seven days a week from 9 a.m. to 8 p.m., southeast corner of Beall Park in Bozeman.
COOKE CITY
Weekly rescue training and snowpack update, 6:30-7:30 p.m., Cooke City Super 8 on Friday, Lulu Pass Road for field location Saturday (Look for the yellow sign).
ENNIS
February 17, 1-hr Avalanche Awareness, 6-7 p.m., Madison Valley Rural Fire Department Station 1.