Bollettino valanghe

Selkirk Mountains

Idaho Panhandle Avalanche Center
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Pericolo valanghe

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

You can trigger a large and dangerous avalanche on all aspects at middle and upper elevations due to a stiffening slab that is overlying weak snow layers. Above freezing temperatures today will help soften the surface snow on solar aspects and make it easier for a skier or rider to trigger an avalanche that could propagate widely across the slope. Give these buried weak layers the respect they deserve and make a simple travel plan that avoids exposure on or below steep open slopes and complex terrain.

Problemi valanghivi

  • Persistent Slabs

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

    Incremental snowfall on January 28th into the beginning of February has built slabs 6 inches to about 1 foot deep sitting on a persistent weak layer. The weak layer of concern is buried surface hoar and sugary faceted snow near a crust that formed in the middle of January. These weak layers may not provide reliable feedback with obvious signs of instability while you're travelling in the mountains, but recent snowpack tests have produced back-to-back results where these weak layers propagated easily across a large column, demonstrating the fragile nature of these snow grains.

    Recent consecutive warm days and surface radiation refreezing at night has allowed for a firm melt freeze crust to develop on the surface. Southerly aspects will soften throughout today from solar input and above freezing temperatures. Slopes that have a softening surface will make it easier for a skier or rider to trigger an avalanche on the buried weak layers that could propagate widely across the slope and connect different terrain features. Persistent slabs are difficult to assess and predict, so to account for this plan on building extra safety margins into your travels by remaining conservative with terrain choices and traveling on lower slope angles under 30 degrees.

    This snow pit from February 3, 2026 demonstrates the current persistent slab problem. Multiple snowpack tests provided unstable results that propagated across the column on the buried surface hoar and weak facets.

    Photo: Jackson George

Avalanche Discussion

On Thursday, February 5th, many of our weather stations reported some of the warmest temperatures we’ve seen so far this season, with most areas across the mountains reaching the upper 40s F and low 50s F. If you were out and about, it probably felt like more of a late spring day as opposed to what we would expect (or hope for) in February.

Today will feature another sunny day with warm temperatures, so long as you climb above the inversion and thick valley fog. Temperatures in the mountains will be slightly cooler than yesterday, but still well above freezing. Clear skies at night have promoted some strong radiational freezing, which is why you might be surprised to find a firm and refrozen surface despite sustained above freezing temperatures at night.

Despite the warm spring weather, the snowpack remains complex, with lurking worrisome weak layers. This is most prevalent and widespread in the northern mountains, and for the next paragraph we will focus on conditions that exist in the Selkirk and West Cabinet Mountains. Down south in the Silver Valley-Bitterroots, things have evolved slightly differently.

Do not be fooled by the lack of recent avalanche activity or potential lack of feedback from surface instability clues. Recent snowpack tests have produced continuous propagating results on the buried surface hoar and facet layers that developed widespread and are now buried about 6 to 12 inches below the surface. These test results really speak to the fragile nature of these weak layers. Natural avalanche activity has been on a downward trend, but human triggering potential remains heightened. This means we land at the “spicy” end of the moderate rating- essentially the upper end of the danger rating. Due to the nature of the weak grains, avalanches could fail from remote trigger or propagate widely across a slope and connect terrain features. The sun working to soften the surface crust will increase the possibility of a skier or rider having an influence on the buried weak layers and triggering an avalanche.

Now in the Silver Valley Bitterroots, we are still finding remnants of the buried surface hoar and facets, but the slab depth above the weak layers is significantly smaller (average 2”-4”) than that in the northern mountains. Because of this, the warm temperatures have had a greater influence on the weak snow in the southern end of the forecast area and is helping to destroy the continuity in those layers. Open areas at higher elevations on north facing aspects with a softer surface are the most likely places to find these weaker layers still intact.

No matter what zone you are in, these weak layers are close enough to the surface that taking a moment to dig down and investigate the snowpack structure doesn’t take a lot of time. If you can identify a distinct grey line, then you are probably looking at a layer of buried surface hoar with weak facets below it, signaling that the persistent slab problem has a good chance of being present. This can offer a quick and helpful snapshot of what’s happening directly below you but should be an ongoing process as you move through the mountains before committing to a slope.  

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