Good Morning. This is Doug Chabot with the Gallatin National Forest Avalanche Advisory issued on Tuesday, December 5th at 7:00 a.m. Today’s advisory is sponsored by Stronghold Fabrication and Highline Partners. This advisory does not apply to operating ski areas.
NEW THIS SEASON: Regional Conditions Pages with region specific weather info, webcams, photos, videos, snowpits and more. Links at top of advisory and in the ‘advisory’ dropdown menu.
Snowfall continued in the northern mountains yesterday measuring 5” in the Bridger Range and 3” in Hyalite and around Big Sky. Westerly winds have increased and are blowing 40-50 mph in the Bridger Range and 15-30 mph everywhere else. At 5 a.m. mountain temperatures are in the low single digits (F) under mostly clear skies. High pressure builds today and skies will remain clear with temperatures reaching 20F and dropping into the single digits tonight. Wind speeds will lessen and remain light through the week.
Storm totals are 14-18" in the Bridger and northern Gallatin Ranges, 10" around Big Sky, and 12" near Cooke City. In areas with the heaviest snowfall amounts, the snow water equivalent (SWE) measured 1-1.5”.
There is much to celebrate: lots of snow, great riding and skiing and mostly good stability. We have not received reports of avalanche activity and overall our snowpack has good structure and strength, which Eric shows in his video from the Bridger Range yesterday. However, there are a few isolated slopes with layers of weak snow found either at the ground or underneath the hard ice crust that formed during the Thanksgiving heat wave. Skiers in the northern Bridger Range on The Throne had a layer under the ice crust propagate in their stability test and decided to ski a different aspect. I found facets on the ground up Buck Ridge yesterday (video) and we cannot forget the deep avalanche that the ski patrol released near the summit of Lone Peak (video) last Thursday. In order to navigate slopes with these rogue weak layers we need to dig and test before skiing in avalanche terrain.
Last night, strong westerly winds blew the new snow into slabs which will be easily triggered. These will be found near ridgelines and in lower elevation gullies. The wind and new snow also grew cornices, which I saw on Buck Ridge (photo). Stay away from avalanche terrain with wind loads and avoid slopes underneath cornices. For today, the avalanche danger is CONSIDERABLE on slopes that are wind-loaded and MODERATE on other terrain.
The southern Madison Range and mountains around West Yellowstone received 6” of new snow. I was in Lionhead a week ago and found most slopes to be stable (video) and capable of handling this new load. The area of concern are wind-loaded slopes near the ridgelines. Winds are blowing 15-25 mph out of the west creating wind slabs that will be possible to trigger. For today, the avalanche danger is MODERATE on wind-loaded slopes and LOW on all others.
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).
Get Avalanche Smart Video Series
The Avalanche Center and Friends group work hand-in-hand to bring you daily avalanche information and education. This last video in series of 4 shows how we create a culture of being safe in the backcountry: Get Avalanche Smart – Episode 4: The GNFAC
Upcoming Avalanche Education and Events
BOZEMAN
Dec. 6, Avalanche Awareness, 6-7:30 p.m. at REI Bozeman
Dec. 7, Avalanche Awareness and Beacon Practice, 6-8 p.m. at Beall Park, Bozeman
Dec. 13, Avalanche Awareness, 6:30-8 p.m. at Gallatin Valley Snowmobile Association, 4-Corners
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
HELENA
7 December, Avalanche Awareness, 6-7:30 p.m. at Basecamp, Helena
WEST YELLOWSTONE
Dec. 14 and 15, Snowmobiler Introduction to Avalanches with Field Course, Info and Register Here
COOKE CITY
8 and 9 December, Current Conditions and Avalanche Rescue, 6:30-7:30 p.m. Friday @ the Super 8, and anytime between 10-2 on Saturday @ Lulu Pass road.
Bridger Bowl is closed and has a backcountry snowpack. This Friday they will open and uphill travel will be prohibited 24 hours/day. If you hike there this week, be aware that ski patrol is on the hill doing setup and avalanche control. Be aware of your surroundings above and below you.