Good Morning. This is Alex Marienthal with the Gallatin National Forest Avalanche Advisory issued on Saturday, January 28th at 7:00 a.m. Today’s advisory is sponsored by Gallatin Valley Snowmobile Association and Excel Physical Therapy. This advisory does not apply to operating ski areas.
The mountains have not received any new snow since Wednesday night. Temperatures this morning are teens to low 20s F, and in the single digits near West Yellowstone. Wind has been out of the west to northwest at 25-40 mph with gusts of 40-50 mph. Strong wind will continue through Sunday, and remain out of the west today at 25-35 mph with gusts to 40 mph. Temperatures today will be 20s to low 30s F. The next chance for new snow is Monday night with more through the week.
Bridger Range
Strong winds have drifted the 11” of snow that fell in the Bridger Range on Wednesday into slabs. These wind slabs formed over low density snow or weak facets and are easy to trigger today. Wind loaded slopes should be avoided. Doug and Eric went to the backcountry north of Bridger yesterday and found widespread cracking and collapsing of wind drifts, and triggered a small slide (video). Skiers in the Northern Bridger Range yesterday reported unstable snow and saw a large natural avalanche near the ridge (photo, snowpit). A skier on Saddle Peak on Thursday trigged a soft slab avalanche that broke 6-18” deep, 30’ wide and ran more than 1,000 vertical feet (photo). Wind blew downhill and across mid-mountain yesterday, in addition to at ridgelines. Expect wind slabs near ridgelines, below cliffs, and on convex terrain features on all aspects and elevations. The avalanche danger today is CONSIDERABLE on wind loaded slopes and MODERATE on non-wind loaded slopes.
Madison Range Gallatin Range Lionhead area near West Yellowstone Cooke City
The mountains south of Bozeman had less snow than the Bridger Range on Wednesday, but there is enough light snow on the surface to form wind slabs. Yesterday, a skier in the Northern Madison Range triggered a 50 foot wide wind slab that ran 800 feet, and Big Sky patrol reported reactive wind slabs up to a foot deep on all aspects. Wind slabs 1-2 feet thick are possible to trigger today. Evaluate terrain and snowpack carefully, and approach wind loaded slopes with caution.
Weak layers of facets and depth hoar near the ground are still a concern. This weak snow has gained strength and has not produced recent avalanches, but there are still some slopes where unstable snow could create a large avalanche. Doug found an unstable slope among many stable slopes at Lionhead earlier this week. He was happy he dug a snowpit before skiing the slope, and went to a different slope (video). Slopes with a shallow snowpack or variable slab depth are most likely to have weak and unstable snow. Depth hoar can produce unexpected avalanches months after it is buried. Evaluate the snowpack before committing to steep slopes. Wind slabs and buried facets make the avalanche danger today MODERATE.
I will issue the next advisory tomorrow morning by 7:30 a.m.
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.
Month of January: Montana Ale Works has chosen the Friends of the Avalanche Center as January's "Round It Up America" recipient. Every time you round-up your bill the change gets donated to the Friends. Pennies equal dollars!
King and Queen of the Ridge, Saturday, February 4th. A Hike and Ski/Ride-a-Thon fundraising event to support the Friends of the Gallatin National Forest Avalanche Center. Register with Bridger Bowl HERE, make pledges HERE.
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.
BOZEMAN
February 1, Women’s Avalanche Awareness, 6-7:30 p.m., REI Bozeman.
February 7, Sidecountry and Avalanche Awareness, 6-7:30 p.m., Beall Park.
February 8, 1-hr Avalanche Awareness, 7-8 p.m., Roskie Hall, Montana State University
February 10 and 11, Companion Rescue Clinic, REI and field day, more info and register here.
WEST YELLOWSTONE
February 4 and 11, 1-hr Avalanche Awareness, 7-8 p.m., West Yellowstone Holiday Inn.
COOKE CITY
Weekly rescue training and snowpack update, 6-7:30 p.m., The Antlers Lodge on Friday, field location Saturday TBA.
DILLON
February 4 and 5, Intro to Avalanches with Field Day, More info and sign up HERE.
ENNIS
February 17, 1-hr Avalanche Awareness, 6-7 p.m.