Boletín de aludes

Selkirk Mountains

Idaho Panhandle Avalanche Center
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Peligro de aludes

Tue
Alta montaña
2 · Moderado
Límite del bosque
2 · Moderado
Bajo el límite
2 · Moderado
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Desactualizado: este boletín caducó last year. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

Wet snow hazards are today’s soup du jour, although the flavor of the hazard may taste a bit different. Rainfall onto an already moist to wet snow surface, following mild overnight temperatures with no refreeze, will eliminate the slow ramp-up of surface softening and maintain an elevated chance to trigger a wet snow slide right out the gate. At upper elevations, wind-drifted slabs of mostly dry, cold snow on northerly and east-facing slopes will take on water like a sponge, soften, and become more prone to fail as a cohesive slab from human or machine disturbance. Steer clear of steeper slopes where you see natural roller-balling, loose sluffs, or you easily punch past boot tops into rotten, manky snow.

Problemas de aludes

  • Loose Wet

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Possible
    Tamaño
    1–2

    The origin of today’s primary wet snow problem is unchanged - the presence of liquid water in the snowpack is helping weaken individual grain bonds - but today’s driver is rainfall versus warm, sunny skies pumping meltwater into the snowpack. While this doesn’t really change things in terms of the “type” of avalanche problem, how to manage the terrain and when to steer clear of the likely places to find trouble will be a bit different. 

    Under warm, sunny skies following a surface refreeze the night prior, we can monitor surface softening and begin to steer clear of sunnier slopes when the snow surface starts to get wet and punchy. Rollerballs and large, slow-moving pinwheels are early indicators that conditions are changing. However, surfaces will start out wet and punchy globally across aspects and elevations from the combination of mild overnight temperatures with no surface refreeze and light, but steady rain to near 7,000 feet.

    If you’re brave enough to tackle the elements, frequently step off your boards or machine and gauge how deep you sink or post hole. Around 8 to 12 inches below the snow surface is a thick refrozen crust from the March 24 rain event. If you start breaking through this interface, it may be easier than you expect to push a larger pile of loose wet snow downhill, and those slides can entrain additional wet, manky snow along the way making a much bigger pile at the bottom.

    (3/26/2025)

    A large, Loose Wet avalanche on a northest-facing slope of Steven's Peak. The slide likely ran during a period of moderate to heavy rain on March 24. Bitterroot Mountains. March 26, 2025.

    Photo: Chris Bilbrey

  • Wet Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Possible
    Tamaño
    1–2

    Snowfall from March 28 to April 3 delivered around a foot of snow across mid and upper elevation slopes. Persistent westerly winds throughout snowfall built slightly deeper slabs on northerly and east-facing slopes. These slabs were stacked above a firm, refrozen crust. While warmer temperatures recently helped take the bite out of these slabs, those same shadier upper elevations slopes stayed cool enough to limit the same wetting effects that other aspects at similar elevation and lower down experienced. Now, these cold, mostly dry slabs are taking on moisture from rainfall Monday and this will likely alter their slab makeup and behavior.

    As former dry wind-drifted slabs soak up Monday’s rain like a sponge, they will slowly soften and may even start to slowly glide above the harder crust below. This change has the potential to make them easier to trigger than their more stubborn dry slab cousins. And if they do fail, they will likely present themselves more like an unpredictable wet slab versus a dry one. Meaning, failure occurs with less warning or none at all, and is more challenging to escape if caught in the moment. Be wary of steep convex rolls and areas directly below ridgelines if you observe active rain-on-snow at higher elevations.

    (3/26/2025) Photo: Idaho Panhandle Avalanche Center

Avalanche Discussion

Recreating and accessing snow at lower elevations has become increasingly difficult as the snowpack continues to shrink, with many slopes below 4,000 feet having melted out. If you do find enough snow to travel or play on there, be especially cautious in gullies or above terrain traps, where even a small avalanche could funnel you into a bad spot and pile up quickly. As you move between 5,000 and 6,000 feet, expect to encounter another transition - springlike, wet snow has recently given way to colder, drier snow sitting atop a firm crust. Be mindful that the flavor and sensitivity of avalanche problems will be in flux within these elevations - especially on aspects where Monday’s rain will soak the drier, colder snow. As usual, the distinct rain-snow line may fluctuate regionally and within the same range with a lower elevation rain line possible across the Northern Selkirk Mountains. 

Wind-drifted slabs may still linger at higher elevations, but you’ll likely need to travel on slopes above 7,000 feet to encounter slopes that avoid the rain. Where they linger, they are likely more of an isolated concern with each passing day. The biggest concern and hazard to manage with older drifted slabs is whether they are simply soaking up the rain and becoming more settled to the crust below, or are they getting wet enough to fail as a more dangerous Wet Slab avalanche. The latter would be the more likely scenario across a broader area given today’s weather, and enhanced by water percolating to the crust and acting as a sliding lubricant.

On a typical spring day, the rate of softening is often dictated and exacerbated by the sun, which gets progressively higher in the sky with each passing day. Rain-on-snow has the potential to accelerate meltwater to weak layers and help soften refrozen crust below, and push wet snow hazards deeper into the snowpack. Continually monitor how punchy or rotten surfaces get to stay ahead of the wet problem game. Slopes where you see large glide cracks, give an extra wide buffer or simply go around. Additional snowpack water weight from rain can push these slopes closer to failure and the timing of glide avalanches is notoriously unpredictable.

In some ways, a spring snowpack can be easier to understand because temperature and solar radiation are key drivers of change. How firm or soft surfaces are at the beginning of your mountain adventure often provides valuable insight into when and where conditions may become dangerous, if at all. Monitor how overall conditions change from start to finish, and avoid high-consequence terrain when stability is in question. Small slides in steep, committing terrain can have serious consequences, so continue to make cautious, well-timed decisions as the season transitions.

**Eastern Oregon University is conducting a survey to better understand avalanche safety preparedness among motorized backcountry users. The survey will help us learn more about who is purchasing, and practicing with avalanche rescue gear (beacon, probe, shovel) and participating in avalanche education—and why some riders are not. The survey is confidential and anonymous. Your feedback is invaluable to improve avalanche education and awareness across North Idaho and Northwestern Montana. Please take a moment to share your experience and help your local avalanche community. You can take the survey HERE.**

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