Good morning. This is Alex Marienthal with early season weather and avalanche information for the Gallatin National Forest Avalanche Center on Friday, November 3rd at 7:00 a.m. This bulletin is sponsored by The Friends of the Avalanche Center and Mystery Ranch. We will issue the next advisory tomorrow morning.
At 5 a.m. the mountains have 2-3” of new snow with 10-12” near Cooke City since yesterday morning. Temperatures are high 20s F, and wind is southwest at 10-20 mph with gusts of 30-40 mph. Temperatures today will be high 20s to 30s F with southwest wind at 15-20 mph. This afternoon, a cold front accompanied by stronger wind will bring heavy snowfall through morning. The mountains will get 6-8” of new snow by tomorrow morning, and intermittent heavy snow will continue through Monday.
November is three days young, but the snowpack could imply it is late December. There is up to four feet of snow on the ground in higher elevations near Bozeman and Cooke City, with 1-3 feet near Big Sky and West Yellowstone. Since Tuesday, the Bridger Range, Hyalite, and Cooke City received 20-26” of snow equal to 2-2.5” of snow water equivalent (SWE); and the mountains near Big Sky and West Yellowstone got 4-8” of snow equal to .4-.8” of SWE.
Wind has drifted recent snow into slabs that are large enough to bury or injure a person if triggered. Wind slabs could be 2-3 feet thick in areas that received more snow. These drifts are likely near ridgelines and on steep, convex terrain. Avoid steep terrain that appears freshly loaded with dense drifts. Even smaller slides can be deadly if they pile deep in a confined gully or creek bed, or if they push a person through trees or over rocks. Many of these terrain traps are prominent right now due to still relatively thin snow cover.
New snow and wind slabs lie over a variety of surfaces ranging from old snow to previously bare ground (video). Avalanches are more likely where fresh slabs formed over old snow, and possible on any slope with enough snow to ski. Slopes that held snow prior to this storm also hold the best skiing, so dig a snowpit to assess stability before travelling into steeper terrain. Two days ago, skiers near Cooke City got unstable, propagating stability test results below the new snow (photo, snowpit). This is a sign to avoid steeper terrain with a similar snowpack for now.
We have had a month and a half of steady snow, but many folks are probably heading out for the first time this season. Check all your gear (fresh batteries), check your partners’ gear, pay close attention to signs of instability such as cracking/collapsing, and carefully assess each slope before committing to steep terrain.
If you get out and have any avalanche or snowpack observations to share, drop a line via our website, email (mtavalanche@gmail.com), phone (406-587-6984), or Instagram (#GNFACobs).
NEW Avalanche Education Video
Check it out! The Friends of the Avalanche Center present the first of 4 short films promoting avalanche education. Ben Goertzen explains why that's important to get avalanche education: VIDEO
Upcoming Avalanche Education and Events
TONIGHT! Ullr and Skadi fest at PhD skis in Bozeman, 7-9 pm. Pray for more snow and support the Avalanche Center. More info HERE.
Billings
7 November, Avalanche Awareness, 6-7:30 p.m. at Basecamp, Billings
BUTTE
17 November, Avalanche Awareness, 6-7:30 p.m., Butte, MT
HELENA
7 November, Avalanche Awareness, 6-7:30 p.m. at Carroll College, Helena
18 November, Avalanche Awareness and Beacon Practice for Snowmobiles, 9 a.m. at Montana Boat Center, Helena
7 December, Avalanche Awareness, 6-7:30 p.m. at Basecamp, Helena
BOZEMAN
6 December, Avalanche Awareness, 6-7:30 p.m. at REI Bozeman
7 December, Avalanche Awareness and Beacon Practice, 6-8 p.m. at Beall Park, Bozeman
Nov. 29, 30 and Dec. 2, 3 or 9, Introduction to Avalanches w/ Field Day, Info and Register Here
Jan. 12 and 13, Companion Rescue Clinic, Info and Register
Jan. 17, 18 and 20 or 21, Introduction to Avalanches w/ Field Day, Info and Register Here
Jan. 24, 25 and 27, Advanced Avalanche Workshop w. Field Day, Info and Register Here
Feb. 9 and 10, Companion Rescue Clinic, Info and Register
COOKE CITY
24 and 25 November, Current Conditions and Avalanche Rescue, 6:30-7:30 p.m. Friday and anytime between 10-2 on Saturday.