This is Alex Marienthal with the avalanche forecast for Sunday, January 19th, at 7:00 a.m. sponsored by Sawtelle Mountain Resort and Ride Rasmussen Style. This forecast does not apply to operating ski areas.
Since yesterday morning, the Bridger Range and Hyalite got up to 1” of new snow, and none fell elsewhere. Wind has been out of the northwest and west at 10-15 mph with gusts of 20-30 mph. Temperatures are single digits above and below zero F.
Today temperatures will be single digits above zero before dropping to negative teens to -20s F overnight. Wind will remain light to moderate from the north and west. Skies will be mostly cloudy with light snow showers during the day. Snowfall will favor mountains near Bozeman, Big Sky and Cooke City with 2-5” of low density snow, and less than 1” is expected elsewhere.
A person can trigger avalanches 2-4 feet deep, or deeper on some wind-loaded slopes, which break on persistent weak layers near the bottom of the snowpack. You are more likely to trigger these big persistent slab avalanches on slopes with snow depths less than 3-4 ft deep. On big slopes where snow depth varies you can trigger one of these slides from a thinner area and it can break wide into a deeper part of the slope. Choose slopes that are non-wind-loaded and with a relatively deep and more uniform snow depth, or stay on slopes less than 30 degrees to keep it simple. Recent avalanches show some of the types of terrain to avoid to minimize triggering a persistent slab avalanche (Red Mountain, Woody Ridge 1, Woody Ridge 2).
Additionally, wind slab avalanches can be triggered where the recent snow has been drifted into soft slabs up to 1-2 feet thick. Assess the snowpack for unstable drifts, assess the terrain for consequences like cliffs, trees and gullies, and remember even a small slide can easily knock you down. Human-triggered avalanches are possible and the avalanche danger is MODERATE near Cooke City, West Yellowstone and in the southern Madison and Gallatin Ranges.
Near Bozeman, Big Sky and Island Park wind slab avalanches can be triggered where recent snow has been drifted into slabs up to a couple feet thick. Watch for drifting snow off ridgelines (photo) and cracking across the snow surface (photo) as signs that fresh wind slabs exist. Older drifts of snow that formed over the last week will be more stubborn, but worth watching out for. Note that strong winds last week formed some drifts in less typical locations like lower elevations.
Avalanches breaking on persistent weak layers are unlikely in these parts of our forecast area. However, buried weak layers do exist, so it is worth choosing slopes with a deeper, more uniform snow depth. See our recent observations from Island Park and Mt. Ellis, and Mark’s video for more info on this unlikely persistent slab problem.
In the mountains around Bozeman, Big Sky, and Island Park the avalanche danger is MODERATE on wind-loaded slopes and LOW on other slopes. Assess the snowpack for buried weak layers and unstable drifts before committing to steep slopes.
KING AND QUEEN OF THE RIDGE
Do you like to hike? Do you like to ski/ride? Then the King & Queen of the Ridge on 2/1 is for you. Hike, ride and raise money for the Friends of the Avalanche Center at Bridger Bowl this year! Join this fun event to promote and support avalanche safety and awareness! Fundraising prizes for the top 5 individuals who raise over $500. No racing is necessary to compete for the fundraising prizes. Info to fundraise is HERE or donate here.
***Race participants for the King and Queen of the Ridge must register separately with Bridger Bowl here***
Upcoming Avalanche Education and Events
Our education calendar is full of awareness lectures and field courses. Check it out: Events and Education Calendar
January 21, 6-7:30 p.m., Women and Girls Avalanche Awareness + Beacon Drills. Story Mill Community Center.
January 23, 6-8 p.m. & January 25, 10 a.m.-2 p.m., Women’s Companion Rescue w/ Sisters of Snow. Required pre-registration and more information HERE.
January 25 or 26, 9 a.m.-3 p.m. Avalanche Fundamentals Field Course. Required pre-registration and more information HERE.
Every weekend in Cooke City: Friday at The Antlers at 7 p.m., Free Avalanche Awareness and Current Conditions talk, and Saturday from 10 a.m.-2 p.m. at Round Lake Warming Hut, Free Rescue Practice.
Thank you for sharing observations. Please let us know about avalanches, weather or signs of instability via the form on our website, or you can email us at mtavalanche@gmail.com, or call the office phone at 406-587-6984.