This is Ian Hoyer with the avalanche forecast for Saturday, January 11th, at 7:00 a.m. sponsored by Yellowstone Club Community Foundation and Montana State Parks. This forecast does not apply to operating ski areas.
New snow totals this morning are:
4-6” (0.3-0.4” Snow Water Equivalent) near Bozeman and Big Sky
2-3” (0.2-0.3” SWE) across the rest of the advisory area
Winds are strong, blowing out of the west (20-30 mph with gusts of 40-60 mph). Temperatures are in the teens F.
Snowfall will continue today and tonight. Snowfall may be heavy at times today around Bozeman and BIg Sky, adding up to 4-6” by this evening. By tomorrow morning, 12-18” are expected near Big Sky and Hyalite, with 6-12” in the Bridger Range. Only 1-2” are expected near Island Park, West Yellowstone, and Cooke City. Winds are forecasted to moderate a little bit, continuing out of the west and northwest.
It is snowing and blowing, and there are weak layers low in the snowpack. This is the perfect recipe for dangerous avalanche conditions.
Wind Slab avalanches will be very easily triggered on slopes loading by the strong winds. In general, expect these slides to break 1-3 ft deep, but they could break even deeper on particularly loaded slopes. Wind Slabs were already seen breaking naturally yesterday (observation and photos) and winds were drifting snow on low elevation slopes that are often untouched by the wind. With more wind and snow, wind slabs will break deeper and be even more easily triggered today.
Will today’s loading be what it takes to see widespread Persistent Slab avalanches? Honestly, I’m not sure - but I do know that it makes me very nervous. Slides breaking on the weak layers in the lower snowpack would be big and destructive. During a big loading event is not the time to test your luck with these weak layers.
Don’t try to outsmart the avalanche hazard today - simply avoid all slopes steeper than 30 degrees and the runouts beneath those slopes as well.
There is some uncertainty in how heavy the snowfall will be today. If the new snow really piles up and the intensity of snowfall spikes we could see dangerous Storm Slab avalanches in places untouched by the wind..
Triggering avalanches is LIKELY and the avalanche danger is CONSIDERABLE today.
Winds have picked up near West Yellowstone, Island Park and Cooke City too, but less new snow has fallen and little more is expected today. This means that wind loaded slopes are the dominant concern in these areas. You could trigger either Wind Slab avalanches breaking within the recently drifted snow or Persistent Slab avalanches breaking on the weak layers lower in the snowpack. Recent avalanches breaking 4-6 ft deep on the weak layers near the ground on Mt. Abundance (photo) and Henderson Mtn. (photo), demonstrate how powerful these slides can be. Slopes without wind affect aren’t 100% risk free, but they won’t have wind slabs to break and the weak layers near the ground have now gotten a decent break from loading, so they are a much safer option.
Cautious route finding is key today. Search out smaller, sheltered slopes untouched by the wind (where the riding should be better anyways) or keep it even simpler by sticking to slopes less than 30 degrees steep.
The avalanche danger is CONSIDERABLE on windloaded slopes and MODERATE on all other slopes.
Upcoming Avalanche Education and Events
Our education calendar is full of awareness lectures and field courses. Check it out: Events and Education Calendar
Avalanche Fundamentals with Field Session for non-motorized travelers during the last weekend of January.
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.
On Tuesday, a skier was killed in an avalanche in Colorado (initial report from CAIC). Last Sunday a skier was killed, and a second sustained injuries in an avalanche in western Wyoming (preliminary information from BTAC). Our hearts go out to the skiers’ friends and family, backcountry partners, and the rescue teams.
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.