More snow and more wind mean that VERY DANGEROUS conditions exist near Cooke City. The good news is that coverage is incredible with nearly 4 feet of snow on the ground. The bad news is that more deadly avalanches will happen. Some avalnches will happen naturally while others will release if you get on or even near a slope steeper than 30 degrees. Stay far away from any steep slope and don’t even go under them.
Most persitent slab avalanches wil be above 9000' but some locations below 9000' may harbor old faceted snow. Exampes are this avalanche at 8600' spotted in Miller Creek and collapsing reported yesterday at 8700' in Republic Creek.
The mountains near Cooke City have been in the bull’s eye for snowfall and avalanches. In the short term, conditions are VERY DANGEROUS. Persistent slab avalanches breaking on old snow near the ground have happened over wide areas like one on Miller Mtn and Henderson Mtn and over smaller areas in smaller terrain. With 5 inches of snow yesterday and more falling today, winds will still have snow to move.
Wind loading will keep many slopes near their breaking point, and you’ll large persistent slab avalanches. Don’t get on or even near any slopes steeper than 30 degrees. Avalanches can be triggered from below and crash down onto you. Today, the avalanche danger in the mountains near Cooke City is HIGH at all elevations.
Most other areas have a similar situation with strong winds whipping snow around yesterday and again today even though they’ve received less snowfall. The Big Sky Ski Patrol triggered avalanches with explosives in areas where they previously hadn’t been able to trigger them. What changed yesterday was strong winds moving snow and creating stiff slabs.
Persistent slab avalanches breaking on old snow from October or late November are still the main threat especially on slopes with wind loading and drifting. Check out Dave’s video from Lionhead yesterday. Wind slabs are a problem too, but the main issue is the extra weight from wind loading that will make persistent slab avalanches more likely.
With recent warm weather, there is a drastically different situation at low elevations where the snow became warm and wet yesterday near Bozeman and Big Sky and likely refroze overnight. It stayed cooler further south towards West Yellowstone where low elevations simply don’t have much snow. They also lack the old snow that has caused persistent slab avalanches.
Today in the Gallatin and Madison Ranges and Lionhead and Island Park areas, with more strong winds coming, the avalanche danger is CONSIDERABLE at mid and upper elevations. The danger is LOW at low elevations.
The Bridger Range has lower elevations than other areas and had above freezing temperatures to almost the Ridge at Bridger Bowl. At upper elevations the avalanche danger is CONSIDERABLE today, while mid elevations have a MODERATE danger where winds should be moving some snow today. At low elevations the snow is either refrozen or still wet depending on how low, and the danger is LOW.
