Good morning. This is Mark Staples with the Gallatin National Forest Avalanche Advisory issued on Thursday, December 26 at 7:30 a.m. A Montana FWP Recreation Trails Grant sponsors today’s advisory. This advisory does not apply to operating ski areas.
This morning temperatures were in the mid 20’s F near Bozeman and Big Sky with winds blowing 15-20 mph and gusting to 30 mph from the S and W. Further south near West Yellowstone and Cooke City, it was colder and calmer with temperatures in the teens F and winds blowing 5-10 mph. Today will have mostly sunny skies, temperatures near 30 degrees F and winds that will increase a bit.
Bridger Range Gallatin Range Madison Range
Lionhead area near West Yellowstone Cooke City
Yesterday a skier triggered an avalanche on Mt. Ellis in the northern Gallatin Range (crown, debris, trees). Fortunately he was able to ski off the slab and was not caught. This avalanche occurred on a NE facing slope and broke on facets about 1ft above the ground. Another avalanche was intentionally triggered near Mt Blackmore in the same range by dropping a very large cornice. Many other slides were seen nearby including one triggered by a goat and another about 1000 ft wide.
In the Bridger Range many slides have been spotted both on the west and east sides of the range, and winds were actively loading the east slopes of Saddle Peak yesterday. Further south the snowpack has the same layering that makes human triggered avalanches likely. A slab of snow rest on weak, faceted snow (aka - sugar snow) generally found about a foot above the ground. Doug and I found this riding in the Taylor Fork area two days ago (video), and Doug and his partner found even worse conditions nearby while skiing near the Bacon Rind drainage yesterday (video). Think of this weak, faceted snow as a layer of dominoes. They only need a skier or rider to tip the first one. Once they all collapse, the slab will release and we’ll get an avalanche. The next few days of warm weather won’t change the situation.
The mountains near Cooke City have fresh wind slabs on many slopes but these are easy to see and avoid. Knowing where buried layers of weak faceted snow exist is much harder because their distribution is not uniform and not all slopes have them. If these faceted layers of snow fracture, the resulting slide will be big and deadly.
Do not trust the snowpack. It has proven time and time again that it will make avalanches. Today human triggered avalanches are likely and the avalanche danger is rated CONSIDERABLE.
I will issue the next advisory tomorrow morning at 7:30 a.m. If you have any snowpack or avalanche observations drop us a line at mtavalanche@gmail.com or call us at 587-6984.
EVENTS/EDUCATION
January 4, BOZEMAN: Saturday, 10:30 a.m. at Bridger Bowl, Free Avalanche Transceiver Workshop, next to rental shop at Jim Bridger Lodge.
January 7, BILLINGS: Tuesday, 6:30-8:30 p.m. at High Mountain Recreation, 90-Minute Rescue Presentation.
January 8, BOZEMAN: Wednesday, 6:30-8 p.m. at REI, Sidecountry IS Backcountry lecture.
January 9, BOZEMAN: Thursday, 6-7 p.m. at Mystery Ranch, 1-hour Avalanche Awareness lecture.
January 9, HELENA: Thursday, 6:30-7:30 p.m. at Exploration Works, 1-hour Avalanche Awareness lecture.
January 11, COOKE CITY: Saturday, 10 a.m. to 4 p.m., Companion Rescue Clinic for Snowmobilers, Pre-Registration is required. https://www.ticketriver.com/event/9445
More information our complete calendar of events can be found HERE.