Silver Valley & Bitterroot Mountains

Snowfall increasing throughout the day will cause the avalanche danger to rise and create new slabs of snow that are 1 to 2 feet thick near tree line and above. These new slabs will be larger and more reactive higher in elevation, where wind has increased slab depth and sensitivity, and hold the potential to step down deeper to buried weak layers. Cracking on the snow surface that extends in front of your skis or board indicates that these slabs could fail from the additional weight of a human and should point you towards sheltered lower angle terrain.   

A small (late) Christmas miracle arrives today with the return of widespread snowfall across the mountains. In the morning, the snow line will hover between 3,000 to 4,000 feet before a steady decrease to valley floors. Upper elevations will likely accumulate anywhere between 8 to 12 inches by sunset, with terrain surrounding the Idaho/Montana border pushing the upper end of that forecast and potentially exceeding it. By the time the storm exits our region and continues its migration, totals could land between one to 2 feet of new snow.

With wind speeds and snowfall rates forecasted to increase later in the day, the avalanche danger will rise in the afternoon as the storm evolves. If you get out in the mountains in search of new snow, stay clued in to the changing conditions. Monitor snowfall rates, observe wind speeds, and tune in to the feedback that the snow surface is relaying to you. These are essential tools to have at the forefront of your mind today, because quick changes or an early arrival of heavy snowfall will increase the danger sooner.

As always, you should be on the lookout for classic red flags of instability. Shooting cracks in front of your feet is one of the telltale signs, along with surface hardness changes or wind textured surfaces. This is all great feedback to help avoid encountering a storm slab, but the persistent slab problem gets a little trickier.

Below the new snow, the snowpack continues to develop a complex array of rain crusts surrounded by weak, faceted snow. As these layers get buried deeper, they are providing less and less feedback. Ultimately, you likely won’t know you are on a slope with this worrisome structure until it’s too late, and you trigger a large avalanche. The best way to be certain is to dig a snow pit and observe the structure, or better yet just commit to low angle slopes that don’t have an overhead hazard. Triggering a relatively small avalanche in the new snow creates the potential to provoke a deeper failure within the snowpack on these weak grains, which would produce a very dangerous sized avalanche.

The silver lining to this situation is that if you avoid travelling in steep terrain and target sheltered slopes, you’ll avoid both of these hazards. Identifying low angle terrain that is less than 30 degrees and that is away from ridgelines could offer up some nice conditions for skiing or riding.