This is Ian Hoyer with the avalanche forecast for Saturday, January 18th, at 7:00 a.m. sponsored by Klim and Cooke City Super 8/Bearclaw Bob’s. This forecast does not apply to operating ski areas.
There are 3-5” of new snow in the Madison and Gallatin Ranges (most of which fell yesterday morning) and 1” elsewhere. Winds are 10-15 mph out of the north and west, with gusts of 20-30 mph. Temperatures are in the negative single digits F.
A chilly, mostly cloudy day is on tap. High temperatures will be in the positive single digits F at best and may stay in the negatives in some places. Winds will be light to moderate and westerly. Snow showers are possible throughout today and tonight. This won’t be much accumulation - a trace in most places and maybe an inch or two around Cooke City.
There are two main avalanche concerns today - avalanches breaking within recently wind-drifted snow and avalanches breaking deep in the snowpack on persistent weak layers 1-2 ft off the ground.
Wind Slab avalanches are most likely in the areas that have more new snow. Keep an eye out for wind drifts deeper than a couple inches. If you find a drift on a steep slope, either steer around it or assess how well it has bonded to the old snow.
You’re most likely to trigger a Persistent Slab avalanche in a thinner snowpack. That could be a lower elevation slope, a thin spot near rocks, or somewhere in the zones around West Yellowstone that generally have a thinner snowpack. While these slides are most likely to start in a thin area, they could propagate out into deeper places and turn into quite a big avalanche. If you want to get into steeper terrain, look for slopes with a uniformly thick snowpack (5+ ft deep) and accept that there is still some possibility you may trigger a slide. Make sure you and your partners all have rescue gear and the rest of your group is watching from a safe spot in case you get unlucky.
Human triggered avalanches are possible and the avalanche danger is MODERATE today.
Around Bozeman and Big Sky, avalanches have become unlikely on slopes unaffected by the wind. With weak layers in the snowpack, there is always some chance of triggering a deeper slide, but you should focus most of your attention on watching out for wind drifts.
As you travel through the mountains today, you’ll find wind drifts that formed at different times over the last week and are bonded to different degrees. Strong winds a couple days were drifting snow at low elevations and in atypical locations, so stay alert even when you’re not up in the normal loading areas near ridgelines. New drifts will likely be thin, but easier to trigger, while older drifts are potentially thicker, but less likely to avalanche. Carefully assess the depth and bonding of drifts before getting into steep terrain. Cracks shooting out in front of your skis or sled are a clear sign of unstable snow and should lead to a quick retreat off steep slopes.
The avalanche danger is MODERATE on wind loaded slopes and LOW on non-wind loaded slopes.
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.