Good morning. This is Doug Chabot with the Gallatin National Forest Avalanche Advisory issued on Tuesday, December 2 at 7:30 a.m. Today’s advisory is sponsored by Javaman and Buck Products. Backcountry conditions exist within the ski area boundary of Bridger Bowl and this advisory is relevant to that area. All other ski areas are closed to uphill travel.
The mountains picked up snow last night, mostly in the south. Cooke City got six inches, West Yellowstone has three inches and all other ranges have a trace to one inch. For the last 24 hours strong westerly winds were averaging 25-35 mph with gusts of 65 mph. Snowfall has ended, the sun will come out and winds will taper off this afternoon. Today, mountain temperatures will reach the upper 20s with clear skies through tomorrow necessitating a smear of sunscreen.
Cooke City
The mountains around Cooke City received .6” of SWE last night with strong winds. Over the last nine days this zone was hit hard with storms and avalanches. Steady snow will help the stability in the long-term, but not the short-term. The immediate problem is a weak layer of facets on the ground that started avalanching after the storms dropped almost 3” of SWE (a couple feet of high density snow) since the weekend before Thanksgiving. The weak layer was very active then and will be less reactive now, but by no means is it stable. Red-flag warnings like cracking and collapsing of the snow are becoming rarer, but triggering a slide on skis or a snowmobile is still likely if you venture into avalanche terrain.
Last Wednesday’s avalanche fatality (video, report) and a seven foot burial on Friday (yes, he lived) are irrefutable evidence that the avalanche danger is real. Given the poor snow structure and recent snow and wind the avalanche danger is rated CONSIDERABLE today.
Bridger Range Gallatin Range Madison Range
Lionhead area near West Yellowstone
A poor snow structure plagues all the mountain ranges in our forecast area (snowpits). Weak, faceted snow at the ground is still misbehaving. On Sunday, Eric got widespread cracking and collapsing in Beehive Basin in the northern Madison Range (video) while I had similar experiences in the Bridger Range at Fairy Lake (video). Yesterday, the Big Sky Ski Patrol triggered avalanches with explosives which are relevant because these slopes have a backcountry snowpack and this is the first time they’ve been tested.
Strong winds have been loading slopes near the ridgelines as well as cross-loading in gullies. Weak snow at the ground is still unstable, especially on steep slopes. For today, the avalanche danger is rated CONSIDERABLE on all slopes steeper than 35 degrees and MODERATE on all others.
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.
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AVALANCHE EDUATION:
Take a look at our Education Calendar for all our classes being offered.
MSU - Introduction to Avalanches with Field Course
The workshops are held on Wednesday and Thursday evenings, with a field course on Sunday. Different topics are presented each evening. Topics include: avalanche terrain recognition, the affect weather has on avalanche hazard, the development of the mountain snowpack, decision making skills, and basic search and rescue procedures.
December 3, 4 and 6 or 7, 2014: https://www.ticketriver.com/event/13089
Snowmobiler Introduction to Avalanches with Field Course
Five hours of lectures are followed by a full day field course. Topics covered include: avalanche terrain recognition, the affect weather has on avalanche hazard, the development of the mountain snowpack, decision making skills, and basic search and rescue procedures.
West Yellowstone: Dec 18 and 19, 2014: https://www.ticketriver.com/event/12955