Cooke City

Look for signs of recent wind-loading like a textured snow surface or cracking, and avoid freshly wind-loaded slopes. Be cautious of steep slopes with a wet snow surface where wet-loose slides are possible, especially in high consequence terrain. Dig down and assess for buried weak layers if you plan to ride steep slopes, and don’t hesitate to back off if you see any concerning signs of instability.

The mountains near Bozeman and Big Sky received 1-2 feet of heavy snow on Thursday and Friday, and strong winds are drifting that snow into thick slabs creating dangerous avalanche conditions. Yesterday in the Northern Gallatin Range, snowmobilers triggered a large avalanche of recent snow and caught it on video which shows a type of dangerous avalanche a person can trigger today. On Friday we got reports of avalanches that broke both naturally and human-triggered during the storm (observation, observation, observation).

Today human-triggered avalanches are likely near Bozeman and Big Sky, especially on slopes where wind has formed fresh drifts. These might be wind slab avalanches that involve recently formed drifts, or persistent slab avalanches could break deeper on layers of sugary facets or surface hoar (observation from Hyalite yesterday). Both are most likely on wind-loaded slopes, but persistent slab avalanches are possible on non-wind-loaded slopes as well. 

Additionally, with temperatures above freezing and some sunshine today, the recent snow will get moist or wet on many slopes which will make it easier to trigger wet-loose or slab avalanches involving the new snow.

Avalanche danger is CONSIDERABLE near Bozeman and Big Sky. Plan to avoid wind-loaded slopes steeper than 30 degrees, and before crossing any steep slopes look closely for signs of instability and assess the consequences of a potential slide.

Since Thursday, near Cooke City, West Yellowstone, and Island Park received 4-6” of snow which is being blown into fresh drifts today. Avalanches are less likely than elsewhere due to less recent snow, but the same types of avalanches as described above are possible with slightly smaller potential size. 

Look for signs of recent wind-loading like a textured snow surface or cracking, and avoid freshly wind-loaded slopes. Be cautious of steep slopes with a wet snow surface where wet-loose slides are possible, especially in high consequence terrain. Dig down and assess for buried weak layers if you plan to ride steep slopes, and don’t hesitate to back off if you see any concerning signs of instability. Avalanche danger is MODERATE near Cooke City, West Yellowstone and Island Park.