This is Mark Staples with early season avalanche information issued Sunday, November 24 at 7:30 a.m. Today’s information is sponsored by Cooke City Motorsports and Yamaha in partnership with the Friends of the Avalanche Center. This information will be updated as conditions change.
This morning mountain temperatures were in the mid to upper 20s F and valley temperatures were in the teens F. West Yellowstone once again had valley temperatures drop below zero F. Winds in the mountains near Bozeman were blowing WNW at 10-15 mph and gusting 20-25 mph. Further south winds were blowing 10 mph and gusting 15 mph. Sunshine and clear skies will be the weather for today with temperatures rising into the mid to upper 30s F. Ridgetop winds will blow from the NW at 15-25 mph. Dry weather should continue through Thanksgiving.
In the Bridger Range, strong downhill winds blew two nights ago and created the primary avalanche problem – wind slabs. A skier on a SE aspect on Saddle Peak yesterday triggered a 6 inch deep slab that broke at the new snow/old snow interface and ran about 1000 feet. Karl found a small avalanche in the Bears area at Bridger Bowl that broke 8-12 inches deep and 25 feet wide at the same interface. Bridger Bowl is backcountry right now even though it may not seem like it. I found the same issue on Thursday on Sacajawea Peak where we were not worried about avalanches breaking deep in the snowpack just within the new snow (video).
Near Cooke City there have been several avalanches (Henderson, CrownButte). This area received over a foot of snow a week ago on Saturday and again on Wednesday. Strong winds accompanied both storms. Avalanches are clear warning signs from Mother Nature that trump all other data. Two slides occurred on Mt Henderson above the Fisher drainage and one occurred on Crown Butte near Daisy Pass. These slides occurred on NE aspects near 9,700 ft and broke over 3 feet deep on weak facets near the ground. At least one of these was human triggered.
Weak facets have been found in many other places like Beehive Basin near Big Sky and Mt Blackmore near Hyalite Canyon (video). This weak, faceted snow exists near the bottom of the snowpack (photo) between snow that fell in October and snow that fell in November. Many of these other areas have not gotten as much snow as Cooke City, thus there is less of a load on these facets. Without a significant load there is not widespread instability; however, facets are never to be trusted. A skier near Sphinx Mountain just south of Big Sky yesterday triggered an avalanche (closeup, overview). It broke on these facets about 8 inches above the ground.
Without any snowfall expected over the next week, the odds of triggering an avalanche will decrease a little every day, and we’ll be in a holding pattern until the next storm. We may form a new weak layer at the snow surface which could be a problem once snow returns, or the next snowfall may activate facets found closer to the ground.
DANGER RATINGS AND FIELD OBSERVATIONS
We will not be issuing danger ratings until we get more data about the snowpack. We need your help. Drop us a line with any of your snowpack observations, pictures or snowpits to mtavalanche@gmail.com. You can also call in your observations in at 587-6984.
EXTRA CREDIT READING
Some recent articles found on our Blog:
Avalanche Safety for Snowmobilers;
The Rules of the Game – safety and strategy in avalanche terrain;
Do phones interfere with avalanche beacons? ;
Staying on top during the Bozeman Ice Festival.
1-Hour Avalanche Awareness Classes
WEST YELLOWSTONE, November 26, 6 p.m. at West Yellowstone Conference Hotel
BOZEMAN, December 2, 7 p.m. at Northern Lights Trading Company
Go to our EDUCATION CALENDAR for details and more courses.
Intro to Avalanches w/ Field Course, MSU; 4, 5 and 7 December
Info and registration: https://www.ticketriver.com/event/7112
Snowmobiler Intro to Avalanches w/ Field Course, West Yellowstone: 19 and 20 December
Info and registration: https://www.ticketriver.com/event/7116