Southern Gallatin Range

Increased wind today will increase the chances to trigger large persistent slab avalanches. Fresh drifts make wind slab avalanches likely for a person to trigger which could be large enough to bury or injure a person. Avoid wind-loaded slopes steeper than 30 degrees, and carefully evaluate the snowpack and consequences of a potential slide before crossing any steep slope. 

We are deeply saddened to report, yesterday a snowmobiler was killed in an avalanche in the Centennial Mountains west of Island Park. Preliminary information is posted on our website, and will be updated as we gather information.

We are deeply saddened to report, yesterday a snowmobiler was killed in an avalanche in the Centennial Mountains west of Island Park. Preliminary information is posted on our website, and will be updated as we gather information. Mark is visiting the site today.

Dangerous avalanche conditions exist in the mountains near Island Park and West Yellowstone. Slopes steeper than 30 degrees should be avoided, including flatter terrain below steep slopes.  Last week’s heavy snowfall created a 2-3 foot thick slab over buried weak layers, and over the weekend we received reports of multiple avalanches that caught and buried, or partially buried, snowmobilers (observation, observation). There was also a skier triggered avalanche near Hebgen Lake (observation). In the Lionhead Area and Island Park avalanche danger is CONSIDERABLE. Avoid crossing on and underneath slopes steeper than 30 degrees.

Further north, and near Cooke City, where less snow fell the hazard has been less widespread, but the recipe for persistent slab avalanches exists (Cooke City video, Hyalite video). In the southern Madison Range, over the weekend we got reports of widespread collapsing of the snowpack (observation), and a skier triggered a large persistent slab avalanche from low angle terrain near Bacon Rind (observation). Increased wind today will increase the chances to trigger large persistent slab avalanches, and the winds will create fresh drifts that make wind slab avalanches likely for a person to trigger which could be large enough to bury or injure a person. Avalanche danger is CONSIDERABLE in the Madison Range, Gallatin Range and near Cooke City. Avoid wind-loaded slopes steeper than 30 degrees, and carefully evaluate the snowpack and consequences of a potential slide before crossing any steep slope.

In the Bridger Range, avalanche danger is LOW and avalanches are unlikely. Remain alert for small wind drifts or wet loose slides if you travel in terrain where a small slide could have high consequences, like above cliffs or steep rocky slopes. This area received the least recent snowfall which drifted into small slabs earlier this week that have mostly stabilized (video). There is minimal snow left to be drifted by today’s winds. Yesterday’s sun and warm temperatures created a crust on sunny slopes which, combined with wind today, will slow the melting of the snow surface and minimize the chances for wet loose avalanches.