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
2 · Moderato
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Non aggiornato — questo bollettino è scaduto last year. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Rain from earlier in the week, yesterday’s warm temperatures and the lack of overnight refreeze mean an increased probability of wet avalanche problems today. Liquid water that has percolated through the upper snowpack has weakened the snow and lubricated layers. Provoking a wet slab avalanche Near Tree Line where liquid water has lubricated layers within the upper 30 to 50cm of the snowpack is a scary possibility today. Complacency over terrain choices could lead to a bad outcome. Over the cuff boot penetration is a good indicator that the upper snowpack lacks cohesion. Avoid convex rollovers where softer snow sits over a harder layer and exposure to terrain traps. Get started early today and if you see rollerballs and pinwheels growing in size, it’s a good time to move to colder snow on non-solar aspects or start heading for the parking lot.

Problemi valanghivi

  • Wet Slabs

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

    With temperatures continuing to rise and the sun making a strong appearance, the likelihood of wet slab avalanches will increase steadily throughout the day. What begins as small, loose wet slides in steep terrain can easily evolve into more dangerous and destructive wet slab avalanches, especially as the snow becomes increasingly saturated. Near tree line is the most likely elevation to find this problem as it has maintained a sweet spot between the extremes both above and below. It has seen greater snow totals than lower elevations with temperatures low enough to preserve layering, but also temperatures warm enough to allow moisture to saturate the upper snowpack.

    Wet slab avalanches today have the potential to be large and consequential—capable of knocking you off your feet, burying you, or carrying you significant distances. To reduce your risk, aim to complete your travel on steep or sun-exposed slopes early in the day. Ideally, be off terrain steeper than 30 degrees by mid-morning. Also take into account slope orientation. North-facing and shaded slopes are less likely to experience rapid warming and generally present a lower risk for wet slab formation. As always, careful route selection, timing, and observation of conditions are key to safe mountain travel in spring-like conditions.

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

  • Loose Wet

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

    The rain and then snow events from early in the week have been followed by sun and daytime highs in the 50's and a lack of overnight refreeze. All these weather phenomina have combined to introduce abundent moisture into the upper snowpack, even at elevation, that has caused the snow to become moist to wet and loose cohesion.

    While the origin of the wet snow hazards seems to be in daily flux - rainfall versus warm conditions driving surface melting - the presence of liquid water in the snowpack is helping weaken individual grain bonds and increasing instability in those layers. 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 may be a bit different. 

    Under warm, sunny skies following a solid overnight surface refreeze, we can monitor surface softening and begin to steer clear of sunnier slopes when the snow surface starts to get wet and punchy. Fresh snowfall has the potential to insulate the older, rain-soaked snow surface and prevent it from locking up despite below freezing temperatures. This could make for elevated odds to trigger a wet snow slide right out the gate. Rollerballs and pinwheels are indicators the snow surface is becoming vulnerable to failure from disturbance, and it’s best to dial back your slope angles or choose one's void of wet, rotten snow.

    Photo: Mikey Church

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.

Today we have thrown wet slabs back into the mix. Where wet loose problems end and wet slab begin are not discreet boundaries, mother nature does not fit into the neat boxes we create to talk about natural phenomena. Near tree line is the elevation band where you are most likely to find the transition as a sweet spot between the extremes both above and below. Here we have seen greater snow totals than lower elevations with temperatures low enough to preserve layering, but also temperatures warm enough to allow moisture to saturate the upper snowpack. Wet Slab avalanches can take skiers/riders by surprise as they often break without warning, can be hard to escape and have debris piles that set up like concrete, so its prudent to treat the threat with respect. Terrain choice and being aware of how conditions are changing around you are the best mitigation strategies: avoid steep, unsupported, convex rollovers and do not venture onto steep slopes that lack cohesion and no longer support the weight of a skier/rider.

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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