Avalanche forecast

Selkirk Mountains

Idaho Panhandle Avalanche Center
View on map

Avalanche danger

Thu
Alpine
2 · Moderate
Treeline
1 · Low
Below
1 · Low
Open full map
Out of date — this forecast expired 2 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

Watch out for freshly drifted slabs below ridgelines and in gullies on northerly and east-facing slopes at upper elevations. On those slopes, elevated westerly winds will efficiently transport Wednesday’s light snowfall into thicker drifted slabs. Back of slopes around 35 degrees if you observe cracking in the snow or the snow surface becomes hard enough to not make an impression below you. Wind-sheltered slopes offer safer riding options.

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely
    Size
    2–3

    Faceted grains persist underneath a couple of older rain crusts two to three feet deep across our forecast zones. The overlying slab has stiffened significantly in the last week and continues to get buried even deeper, increasing the difficulty of impacting these weak grains. Where the crust has degraded and is more breakable, the facets are overall larger and weaker. Your chances to trigger one of these lower-probability, higher-consequence slides increase near exposed rocks or wind-scored areas of slopes where these weak snow grains may be closer to the surface.

    Persistent slab avalanches can behave unpredictably and span across adjacent terrain features. Choose slopes free of surface obstacles or terrain traps just in case something goes wrong. Default to lower-angled slopes if your snowpack assessments are inconclusive around the sensitivity of faceted crusts.

    Multiple rain crust exist in the top meter of the snowpack. These crust/ facet combos have become very stubborn to fail in tests and you likely need to find a shallow spot to impact these weak grains below a stout slab.

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–2

    The combination of increased winds and new snow will result in wind slabs developing below ridge lines and cross-loaded gullies. Winds will initially be from the southwest then shift to the west. This will broaden slab formation across northerly and east-facing slopes - maybe becoming more isolated on southeast-facing slopes. Likely shallow and soft in nature, these new slabs are identified by a lens-shaped apperance and where the snow surface quickly transitions to stiffer, more dense snow. Cracks extending infront of your boards or machine are also clues you could be standing on a concerning drift. Places where drifted slabs form above harder surfaces, those slide can break wider than you expect and more easily knock you over and take you for a ride.

    A shallow natural slide that failed on a west-facing slope from recent easterly winds. Deeper drifts are likely found near ridgelines and in gullies at upper elevations.

Avalanche Discussion

The much-welcomed sunshine will experience a brief intermission today with the arrival of a weak system bringing in very modest amounts of new snow to the mountains. As our weather transitions, our focus for avalanche hazards shifts to the upper portion of the snowpack and new snow related problems. Variable winds with speeds that are sufficient enough to transport new and existing snow will create fresh wind slabs in upper elevation terrain. Due to the changing wind direction, these denser slabs will extend their reach and build throughout the day.

While snowfall numbers are not overly impressive in the next 24-hours, there is ample dry and cold snow sitting in windward fetches to quickly get transported onto lee slopes and form more problematic slabs. This all hinges on how fast or long the wind blows for. Broad openings have better odds at developing larger hazards quicker than more treed areas near the timberline where similar slabs may be more isolated. You can use small, test slopes to inspect sensitivity of fresh drifts before venturing out into steeper, bigger slopes or simply stick to wind-sheltered areas and lower elevation terrain.

WIth each passing day, deeper faceted grains continue to become more sleepy, but not totally in a state of dromancy just yet. The weight of the slab sitting above numerous faceted rain crust is likely helping compress these interfaces and take the bite out of them. The further these weaker interfaces sit below the surface, the less likely it is for a rider to impact them and trigger a slide. Maybe it takes a larger trigger like a snowmobile trenching thorugh the slab or a large cornice caving off from above? Or maybe it requires finding the shallow spot on a slope to awaken the sleeping monsters?

During times of lower-likelihood, higher consequence we often rely on solid terrain management to help offset the realm of uncertainty. With less frequent field observations above 7,000 feet lately, know that venturing higher in elevation could push you into terrain where these faceted grains may be more preserved but the slab above will likely be thicker and stiffer. Avoid steep, rocky places where more trigger spots are abundant on a slope, and pick slopes free of vegetated runouts or terrain traps to account for the "what-if" scenario. Be mindful of other groups recreating around you and only expose one person to a slope at a time.

Regions covered