Good morning. This is Eric Knoff with the Gallatin National Forest Avalanche Advisory issued on Sunday, December 20, at 7:30 a.m. Today’s advisory is sponsored by Bozeman Ski Guide and Buck Products. This advisory does not apply to operating ski areas.
AVALANCHE WARNING
The Gallatin National Forest Avalanche Center is continuing a Backcountry Avalanche Warning for the mountains near Cooke City, the Madison Range, the Gallatin Range, the Lionhead area near West Yellowstone, and the Bridger Range. Continuous snowfall and strong winds have added weight and stress to a weak and unstable snowpack. Natural and human triggered slides are likely today. Avalanche terrain including avalanche runout zones should be avoided. The avalanche danger is rated HIGH on all slopes.
AVALANCHE FATALITY
The GNFAC is sad to report that a snowmobiler from North Dakota died in an avalanche yesterday outside of Cooke City. The avalanche occurred on the SE face of Sheep Mountain between Lulu Pass and Round Lake. The slide was triggered by the victim who was buried six feet deep under his sled. The victim had an airbag but was unable to deploy it. The slide also caught two other party members who were parked in the run out zone. One was buried to his chest while the other was completely buried. They both deployed their air bags and escaped relatively unharmed. Our deepest condolences go out to the victim’s family and friends.
Doug and Alex will visit the accident site today. We’ll provide a more detailed report once we gather more information.
Over the past 24 hours the mountains picked up 6-10 inches of new snow. At 4 a.m. snow has stopped falling and temperatures range from the single digits to mid-teens F. Winds are blowing 5-15 mph out of the W-SW-NW. Today, southwest Montana will see a break in the weather. Skies will be partly to mostly cloudy and temperatures will warm into the upper teens to low 20s F. Winds will continue to blow 5-15 mph out of W-SW. There is a slight chance of snow showers in the mountains around West Yellowstone and Cooke City today, but no real accumulation is expected. A weak storm system moves into the area tonight bringing a better chance of snow to the mountains south of Bozeman. The mountains around Big Sky, Cooke City and West Yellowstone should see 2-4 inches by tomorrow morning while the Bridger Range will likely see 1-2 inches.
Bridger Range Madison Rang Gallatin Range
Lionhead area near West Yellowstone Cooke City
Since yesterday morning, the mountains picked up 6-10 inches of new snow totaling .5-.8” of SWE. This additional load will be increasing the stress on an already overwhelmed snowpack (video, video, video). Over the past five days, multiple natural and human triggered avalanches have been reported. The fatality outside of Cooke City falls on the heels of numerous other incidents and close calls. Here is a list of the most notable events over the past week:
- Tuesday, six human triggered avalanches were reported outside of Cooke City. One caught and partially buried two snowmobilers. Fortunately both were unharmed.
- Tuesday, Doug and Alex observed a natural avalanche in Sunlight Basin in the Southern Madison Range (photo).
- Thursday, Doug and his partner remotely triggered an avalanche on Mt. Ellis (photo).
- Thursday, snowmobilers triggered multiple slides up Cabin Creek in the southern Madison Range (photo).
- Friday, a snowmobiler trigged a slide on Buck Ridge in the northern Madison Range.
- Friday, three natural avalanches were observed in the Bridger Range. One in Argentina Bowl (photo) and two on the west side.
- Yesterday, a skier was caught and carried in an avalanche near Big Sky in the northern Madison Range.
- Yesterday, the Big Sky and Yellowstone Club Ski Patrols triggered large avalanches during control work.
These avalanches are clear, bulls-eye information the snowpack is being pushed past its breaking point. What's tricky about the current snowpack situation is the upper layers of the snowpack (the slab) are now becoming thick and nearly supportable. This can provide a false sense of security because the snowpack may feel strong and stable. Don’t be fooled! The snowpack is still highly unstable and should not be trusted.
Today – Natural and human triggered avalanches are likely and the avalanche danger is rated HIGH on all slopes. Avalanche terrain including avalanche run out zones should be avoided.
SNOTEL sites in SW Montana are not working which impedes our ability to report snowfall amounts. NRCS is working hard to fix this issue soon.
I will issue the next advisory tomorrow morning at 7:30 a.m. If you have any snowpack or avalanche observations to share, drop us a line at mtavalanche@gmail.com or leave a message at 587-6984.
EVENTS and AVALANCHE EDUCATION
A complete calendar of classes can be found HERE.
Cooke City: December 23, 1hr Avalanche Awareness, Cooke City Visitor’s Center, 6-7:30 p.m.
West Yellowstone: January 2, 1hr Avalanche Awareness, West Yellowstone Holliday Inn, 7-8:30 p.m.
Bozeman: January 6, Women’s Avalanche Awareness and Beacon 101, Beall Park, 6-8 p.m.
January 9 and 10, Companion Rescue Clinic, REI, Fri 6-8p.m., Sat 10a.m.-2p.m.
January 13, 1hr Avalanche Awareness, REI, 6-7:30 p.m.
Livingston: January 14, 1hr Avalanche Awareness, Neptune’s Brewery, 6-7:30 p.m.
Dillon: January 19, 1hr Avalanche Awareness, UM Western Library, 6:30-8 p.m.
ASMSU Intro to Avalanches w/ Field Course
January 20, 21 and 23 or 24: https://www.ticketriver.com/event/16861
The workshops will be held on Wednesday and Thursday evenings, with a field course on either Saturday or Sunday. Different topics will be presented each evening. Topics include: avalanche terrain recognition, the effect weather has on avalanche hazard, the development of the mountain snowpack, decision making skills, and basic search and rescue procedures.