Good morning. This is Eric Knoff with the Gallatin National Forest Avalanche Advisory issued on Sunday, January 6 at 7:30 a.m. Today’s advisory is sponsored by Montana Ale Works in partnership with the Friends of the Avalanche Center. This advisory does not apply to operating ski areas.
There is no new snow to report, but a weak weather disturbance could deposit a trace to one inch of snow by this afternoon. This morning mountain temperatures are in the 20s F with the exception of the West Yellowstone area where temperatures are in the single digits. Winds are blowing 15-30 out of the WSW with gusts in Hyalite reaching close to 50 mph. Today, temperatures will warm into the upper 20s to low 30s F and winds will continue to blow 15-30 out of the WSW. There is a chance of mountain snow showers through the day, but accumulations will be light. A stronger storm system is forecasted tomorrow night into Tuesday.
Bridger Range Madison Range Gallatin Range
Lionhead area near West Yellowstone Cooke City
Taking time to assess snowpack and terrain can be difficult when generally safe avalanche conditions exist. However, assuming all slopes are safe during a low avalanche danger can be costly. This was demonstrated by the human triggered avalanche in the Hourglass chute north of Bridger Bowl on Thursday (video, video, photo1, photo2). This slide occurred on a slope where a wind slab formed over a thin layer of facets. While investigating the slide on Friday, both Mark and I felt this chute was one of the few places in the area with unstable snow.
Today, wind slabs resting over facets are the main avalanche concern. While generally green light conditions exist in most areas, a slab-facet combination can be found on isolated slopes in exposed, upper elevation terrain (photo). The challenge today will be figuring out which wind loaded slopes have buried weak layers and which do not. If you’re not willing to dig a snowpit, then it’s probably best to avoid the most dangerous slopes – the ones steeper than 35 degrees that drain over cliffs or into gullies or trees.
NEW WEAK LAYER
Recent dry weather has faceted the snow surface in many areas (video, article). Yesterday, I skied in the southern mountains near West Yellowstone and found a well-developed layer of near surface facets on all aspects and elevations. This layer has also been observed in the mountains near Bozeman and Big Sky as well as the Cooke City area. Currently, this layer does now pose a major avalanche threat, but once a slab of snow builds on top of it, we’ll have the right recipe for avalanches.
Today, generally safe avalanche conditions exist and the avalanche danger is rated LOW.
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.
Tuesday, January 8, 7:00 p.m., 1-hour Avalanche Awareness at Big Timber High School.
Wednesday, January 9, 6:30 p.m., 1-hour Avalanche Awareness at REI, Bozeman.
Thursday and Saturday, January 10 and 12, Rescue Clinic. Thursday at 6:00 p.m. at REI, Bozeman and Saturday at 10 a.m. in the field, location TBD. For more info and to register go http://www.rei.com/event/47692/session/64126
Saturday and Sunday, January 12 and 13, Snowmobiler Introduction to Avalanches with Field Course in Bozeman. Currently we only have four people registered and need ten to run the course. We will cancel the course if 6 more do not register by Monday afternoon, January 7. For more information and to sign up: https://www.ticketriver.com/event/4979-snowmobiler-introduction-to-avalanches-w-field
Wednesday, January 16, 7:00 p.m. “The Sidecountry is Backcountry” at MSU’s Procrastinator Theater in Bozeman, a free 1-hour presentation.
Saturday, January 19, Rescue Clinic for Snowmobilers in Cooke City starting at Cooke City Motorsports. This 6 hour clinic teaches how to use avalanche rescue gear and perform an avalanche rescue. Registration is required. For more info and to sign up, visit: https://www.ticketriver.com/event/4980-companion-rescue-clinic-for-snowmobilers