Good morning. This is Eric Knoff with the Gallatin National Forest Avalanche Advisory issued on Monday, December 1st at 7:30 a.m. Today’s advisory is sponsored by Alpine Orthopedics and World Boards. Backcountry conditions exist within the ski area boundary of Bridger Bowl and this advisory is relevant to that area. All the other ski areas are closed to uphill travel.
Over the past 24 hours no new snow has fallen. This morning a weak ridge of high pressure is parked over the region producing clear skies and a strong temperature inversion. Currently, mountain temperatures are 10-15 degrees F warmer than the valley. Most mountain locations are in the upper single digits to low teens F and winds are blowing 10-20 mph out of the WSW. Today, skies will start out mostly clear but will become partly to mostly cloudy by this afternoon. Temperatures will warm into the mid-20s to low 30s F and winds will steadily increase out of the WSW. A weak weather system will impact the area tonight and tomorrow producing an increased chance of snow. Cooke City will likely receive 3-5 inches by mid-day tomorrow. The mountains around West Yellowstone could see 2-4 inches with the mountains around Big Sky and Bozeman picking up 1-2 inches.
Cooke City
The avalanche warning for the mountains around Cooke City has expired, but dangerous avalanche conditions still exist. Facets near the ground will continue to feel the stress from the most recent storm and still hold to potential to produce large and dangerous avalanches. There is now a dense slab sitting on these facets and it will still be possible to trigger slides remotely (from a distance). At this time I would continue to avoid slopes steep than thirty degrees, especially if they are attached to larger steeper slopes.
Remember – It has only been six days since the avalanche fatality on Henderson Mountain (video) and only four days since a full burial, also on Henderson Mountain.
Today – Human triggered avalanches remain likely and the avalanche danger is rated CONSIDERABLE.
Bridger Range Gallatin Range Madison Range Lionhead area near West Yellowstone
A poor snowpack structure continues to produce obvious signs of instability. Yesterday, my partners and I toured into Beehive Basin north of Big Sky and experienced widespread cracking and collapsing (video). We completely changed our plan and kept slope angles below thirty degrees. Doug also experienced cracking and collapsing in the northern Bridgers and got unstable results in stability tests (video). Skiers found similar conditions at Bridger Bowl.
- What are these signs telling us? The snowpack is unstable and should not be trusted.
- What now? Avoid avalanche terrain. If stability is the question then terrain is the answer. Keep slope angles below thirty five degrees and always pay close attention the terrain above and below you.
Although signs of instability will gradually decrease as the snowpack adjusts to the most recent load, I would not accept this as a green light to push it in avalanche terrain. Facets near the ground will take time to heal and will remain a problem through the foreseeable future.
Today - A poor snowpack structure and recent signs of instability make human triggered avalanches likely on slopes steeper than thirty five degrees which have a CONSIDERABLE avalanche danger. Slopes less steep slopes have a MODERATE avalanche danger.
AVALANCHE FATALITY
A snowmobiler died in an avalanche outside Cooke City last Wednesday. Read the full accident report here: Accident Report
If you get out please let us know what you find. You can drop us a line at mtavalanche@gmail.com or give us a call 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 Saturday. 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