Cooke City

There are a wide range of conditions with some slopes more likely to produce an avalanche than others. Most slopes have a persistent weak layer buried 2-3 feet deep that can produce a persistent slab avalanche. In the last two weeks, there have only been two days when avalanches haven’t occurred at least somewhere in the forecast area. 

The danger is generally MODERATE because the overall likelihood of triggering an avalanche has dropped but there’s still a good chance of triggering a slide. Avoiding slopes steeper than 30 degrees without overhead hazard is the easy way to avoid avalanches entirely.

Now is a tricky time to get into avalanche terrain. The avalanche danger is MODERATE across the forecast area, BUT that is a very broad, generalized rating of conditions. In some places there’s a good chance you’ll trigger an avalanche while not so much in other places. 

The main issues are buried, weak faceted layers 2-3 feet deep and recent strong winds (Sun & Mon) that drifted a lot of snow that fell at the end of last week. Persistent slab avalanches are the primary problem because of those buried weak layers - mostly facets that formed in January, some that formed in February, and some surface hoar that formed in February. 

Avalanches have happened  nearly every day over the last two weeks. There have also been reports of collapsing and cracking. Notable recent slides include:

• West side of the Bridgers yesterday - triggered remotely, 1.5 ft deep.
• Portal Creek in N. Gallatins on Sunday that Dave checked out yesterday (video), 1-2 ft deep, 700 ft wide.
• Dudley Creek in N. Madisons on Sunday - skiers found a recent snowboard triggered slide 9 in deep, 200 ft wide.
• LIttle Bear area of N. Gallatins on Saturday - snowmobilers triggered a slide from below the slope (video of avalanche happening)
• Just south of Cooke City on Monday, skiers spotted a recently triggered slide

Persistent slab avalanches are the problem today. They will be more likely on slopes with loading and drifting from recent winds, but they may happen on slopes sheltered from winds as well. In many cases, the weak layer is much much weaker on sheltered slopes.

What are your options? Ian discusses a few options in this video.

• Personally, I just don’t trust the snowpack and would generally avoid getting on any slope steeper than 30 degrees. I wouldn’t get near the toe of a slope steeper than 30 degrees either. There is too much uncertainty for me to feel good about riding steep slopes.
• If you do choose to get onto steeper slopes: (1) pick smaller slopes that will make smaller avalanches, (2) pick slopes with a clean runout free of gullies, trees, or rocks that make avalanches much more deadly, (3) dig a quick snowpit nearby in safe terrain looking for buried weak layers and do snowpack tests - avoid steeper terrain if you see these weak layers and/or get poor test results.
• As always, MAKE SURE to travel with a partner who can watch you from a safe location and knows how to use their avalanche rescue gear. A solo skier was killed in a slide in Colorado on Saturday.