Bollettino valanghe

Selkirk Mountains

Idaho Panhandle Avalanche Center
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Pericolo valanghe

Mon
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
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In sintesi

The addition of rain and wet snow to cohesive slabs over vulnerable weak snow layers keeps an elevated chance to trigger a large, dangerous avalanche. At higher elevations, slightly deeper snowfall and the influence of stronger winds may be exacerbating the problem further, and where avalanches can propagate widely across slopes. With how fragile the weak snow is below, provide yourself with an extra buffer adjacent to or directly below slopes around 35 degrees to account for triggering an avalanche from a distance.

Problemi valanghivi

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–2

    Two to six inches of wet snow and around half an inch of Snow Water Equivalent has added more stress to buried surface hoar and facets below a crust. The new load is not expected to contribute to an uptick in natural avalanche activity, but it could be enough to make human triggering a bit easier than the day prior. These weak layers are particularly problematic because they may not produce obvious warning signs, such as cracking or collapsing, before you trigger an avalanche. 

    Recent snowpack tests have repeatedly provided us with easy propagation results across large columns, highlighting the lingering reactivity in these weak layers and the dangerous consequences that may ensue. If a slide breaks as widespread across the terrain as these grains exist, those slides will be very difficult to escape. The biggest challenge of the Persistent Slab avalanche problem is managing the uncertainty around the known unknowns. Be mindful of your terrain choices and favor slopes around 30 degrees without steeper hazards directly above.

    Slab depth in our west aspect snow pit was around 10 cm thick. Recent warm temperatures have dramatically helped stiffen the slab over the surface hoar. Where slabs are either stiffer from drifting, or the recent warm-up, or deeper in total depth (closer to 30 cm), are where we've been observing the most consistent propagating failures. Selkirk Mountains. February 6, 2026.

    Photo: Chris Bilbrey

Avalanche Discussion

Snow totals range 2 to 5 inches in the Selkirk Mountains, 3 to 6 inches in the Cabinet Mountains, and 1 to 2 inches in the Purcell and Bitterroot Mountains. Snow densities were generally 16 to 20 percent. The Hidden Lake and Bear Mountain SNOTELs report 0.8 inches and 1.1 inches of SWE respectively. Most other SNOTELs report around half an inch of SWE.

The new snow and water amounts are not expected to increase the natural avalanche threat today but it does move the triggerability needle to a little higher potential. Not all the way to CONSIDERABLE (3of5) danger but definitely in the “spicey” MODERATE (2of5) realm. That is, a somewhat stubborn slab-weak layer problem broadly speaking, but one that carries big consequences because of the widespread distribution of the weaknesses below.

The tricky part about our current Persistent Slab avalanche problem is not the lack of weak layers in the upper snowpack. It’s the slab depth variable, which appears to be a primary driver of whether or not you could trigger a slide. Slab properties that produced propagating results in snowpack tests don't fit the same criteria. It's been a combination of slab depth and stiffness, and the flavor of persistent grain below (surface hoar versus facets below a crust) that need to line up to complete the avalanche recipe. If those variables align together and you travel on a steep enough slope, odds are you can trigger a dangerous avalanche.

Outside of propagating ECTs and sudden planar CTs, other signs of unstable snow like long shooting cracks or audible collapses waned during the most recent warm-up. This has only masked the danger below but by no means eliminated the hazard. Some had hoped that Saturday’s rain would be enough to wet or disturb the buried surface hoar, but rain totals appear too light to drive a pulse of water deep enough. Even slab settling over the last week did not effectively squash the surface hoar on top of the crust or compress the facets below the crust to be non-issue. They merely persist waiting for the extra nudge from the wrong spot.

Continue to travel with a healthy dose of suspicion on the majority of aspects at mid and upper elevations. We chose to pull the Persistent Slab avalanche problem from south and southwest aspects at middle elevations on February 8. Those aspects warmed and consolidated the most during the last warm spell and we anticipate the return to colder weather will help take the bite out of our snowpack concerns there. Those same aspects above 6,500 feet should be treated differently as the more recent weather may not have provided the same snowpack settling benefits as lower in elevation.

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