Island Park

It’s great to see snow falling, but the danger will be rising today as new snow piles up and stresses buried weak layers. There will be multiple overlapping avalanche problems creating dangerous avalanche conditions mostly on slopes with wind-blown snow. The safest terrain choice will be slopes less than 30 degrees in steepness with nothing steeper above.

Before today’s snowfall, the avalanche situation was already a bit tricky with avalanches continuing to occur like some in Cooke, one in the S. Madison Range, near Hyalite, and near Lionhead. Yesterday while riding just south of Big Sky, my partner and I experienced collapsing and cracking, and just nearby a skier remotely triggered a slide from 80-100 feet below, all on weak, faceted snow from the dry January (observation). 

The snowpack in almost all areas has layers of weak faceted snow (1-2 feet deep but getting buried deeper today) from the dry January and periods of dry weather in February. Slopes with some sun exposure have ice crusts as well which aren’t good or bad, but the facets have been preserved under those crusts. 

Loading from today’s snowfall will stress these weak layers especially in areas with about a foot of new snow where persistent slab avalanches will be likely on all slopes. There will also be wind slabs forming where winds from the NW will be drifting snow. The avalanche danger in the Northern Madison and Northern Gallatin Ranges will rise ⬆️ to CONSIDERABLE as new snow piles up. 

Further south in the Southern Madison & Southern Gallatin Ranges and the Lionhead/Island Park/Cooke City areas, less snow is expected and the danger should rise ⬆️ to CONSIDERABLE at higher elevations where NW winds will be drifting snow. This wind loading will form sensitive wind slabs and also add enough additional loading to make persistent slab avalanches likely.

Don’t let your guard down in the Bridger Range just because it has been so hot and dry lately. By later today if new snow depths get closer to a foot, storm slab avalanches could become likely especially during periods when it’s snowing hard. Wind slab avalanches will certainly be likely near ridgetops. The wild card will be persistent slab avalanches which haven’t been an issue in the Bridgers for most of the winter. HOWEVER, both Dave and another party found buried surface hoar about a week ago 4-10 inches deep just north of Bridger Bowl. That layer could wake up and produce surprising avalanches. Today in the Bridger Range the avalanche danger will be rising ⬆️ to CONSIDERABLE. 

Travel advice: With snow falling today, widespread buried weak layers, and north winds, I’ll be staying out of avalanche terrain today and enjoying the new snow on slopes less than 30 degrees in steepness. Yesterday’s persistent slab avalanche triggered by a skier low on a slope is a good reminder to avoid being under steep slopes as well.