Silver Valley & Bitterroot Mountains

Above freezing temperatures and rising freezing levels will creep up the mountain and wet the most recent snow, which may create the possibility for wet snow sluffs on steep slopes. Although these avalanches will be small, they could run longer distances in complex terrain or gullies where the surface crust is firm and creates a slick sliding plane. Avoid travelling in runout zones and crossing below large cliff bands if you see small sluffs gaining in size as it moves downhill or pinwheels naturally releasing.  

Following an 18-day dry spell that lasted for the majority of January, the mountains have seen a plethora of changes in the past couple of days- periods of snow, rain, wind, and now increasing freezing levels.

Temperatures on Saturday will be warm and are forecasted to reach the upper 30s F in the northern end of the forecast region and the low 40s F in the southern end. Throughout the day, the freezing level will rise to 6500’-7000’- Potentially exceeding the tallest peaks in the Silver Valley-Bitterroots. Cloud cover will persist during the day, but the above-average temperatures will make the mountains feel like it’s spring (again). This warm-up will introduce the possibility of Wet Loose avalanches on all aspects in steep terrain. Because recent storm totals aren’t very large, these avalanches are expected to be small. However, these slides could run farther distances than expected and could pose a greater consequence if they catch you off guard in complex terrain.

In the wake of new snowfall, field teams this week have set out with the intentions of documenting where the surface hoar that developed during dry January has been preserved. In the Selkirk and Cabinet Mountains, this worrisome weak layer is buried under approximately 6”-8” of new snow, with slabs being closer to 12” in drifted areas at mid and upper elevations. (Obs from 1/30) Snowpack tests show that this developing slab doesn’t have quite enough weight to fully propagate on its own yet, but areas where the wind has transported the snow and created denser slabs will be more sensitive to the added weight of a skier or rider and can more easily produce an avalanche. Because of the nature of these persistent weak grains, these avalanches could break wider than expected and be large, especially if the surface hoar was preserved sitting on a firm crust. No doubt this is a concerning setup.

Field teams in the Silver Valley-Bitterroots (Obs from 1/29) found that less snow and warmer temperatures helped destroy some of this buried surface hoar below tree line. However, the surface hoar was found preserved above 6300’ by a couple of inches of snow. No matter what zone you are recreating in, consider digging several hand pits to try to locate these buried feathers before stepping onto and committing to a steep slope. A thin and distinct grey line below the recent snow indicates that this worrisome setup is present. Cracking in front of your skis or boards is also a clear indicator of avalanche potential.

Make sure to keep your avalanche brain engaged and continue to use good travel habits. If you get out and about, please consider dropping us an observation HERE or through the AvyApp. Something as simple as describing the weather and surface conditions goes a long way to help our forecast products and your local avalanche community. We have received some very helpful public observations recently, and we look forward to more.

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