Island Park

Avalanches 1-2 ft deep can easily be triggered today especially on slopes raked by yesterday’s howling winds which are almost all open slopes. More snow falling today with some gusty winds will keep things dangerous. Also, with poor visibility you may not see recent avalanches and may not get signs of instability like collapsing or cracking if riding in areas that had lots of old tracks. Don’t let a lack of clues lull you into a false sense of security.

Despite varied snowfall amounts, strong winds drifted snow in all areas producing natural and human triggered avalanches:

• Dave and I rolled up just after a rider remotely triggered a slide (not caught) off the north side of Reas Peak near Island Park. We triggered a small wind slab and spotted about 5 others.
• A rider near West Yellowstone under Lionhead Ridge triggered a slide from below a steep slope and was caught but not injured.
• In Hyalite Canyon, a skier spotted a natural avalanche 1-2 feet deep and ~200 ft wide near Maid of the Mist Mtn.
• In the backcountry terrain near Big Sky in Lone Lake Cirque a large natural avalanche over 300 feet wide happened. 
• Just south of Cooke City, Alex experienced shooting cracks on wind loaded slopes.
• On Monday, north of Cooke City near Wolverine Peak, guides spotted one natural avalanche and triggered another. 
• On Monday, a natural avalanche just north of Bridger Bowl was spotted.
• On Monday, along Buck Ridge just south of Big Sky a wind slab resting on facets on a small slope broke over a surprisingly far distance (video).

Any slope touched by yesterday’s howling winds (which is almost every open slope) will likely produce an avalanche 1-2 feet deep today. A wide spread layer of facets underneath the recent snow and wind drifted snow will allow avalanches to break over much wider areas and be triggered remotely. Snow falling today may camouflage visual signs of wind effect on slopes.

Where it gets tricky is on the few sheltered slopes that were untouched by yesterday’s winds. Persistent slab avalanches can be triggered on these sheltered slopes mostly in places that received the most snow near West Yellowstone, Island Park, Southern Gallatin and Madison Ranges. Popular areas like Bacon Rind and Trapper Creek near Hebgen Lake will be especially sensitive as they produced slides (like this one last week) and collapsing/cracking prior this snowfall. 

Today throughout the forecast area the avalanche danger is CONSIDERABLE. It’s a great time to get out and enjoy the fresh snow, but these are dangerous avalanche conditions requiring careful route finding and terrain selection. There are almost no steep slopes I’d feel comfortable riding today, and the safest option is to choose slopes less than 30 degrees in steepness with nothing steep above you.