Boletín de aludes

Snoqualmie Pass

Northwest Avalanche Center
Ver en el mapa

Peligro de aludes

Sat
Alta montaña
3 · Notable
Límite del bosque
3 · Notable
Bajo el límite
2 · Moderado
Open full map
Desactualizado: este boletín caducó last year. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

A more potent, wetter, and warmer storm will impact Snoqualmie Pass Thursday night into Friday, creating dangerous avalanche conditions. Human-triggered and natural avalanches are expected - both dry and wet, loose and slab. So make conservative travel plans and be prepared to avoid slopes over 35 degrees where triggering an avalanche is more likely.

Problemas de aludes

  • Storm Slabs

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

    Friday will be similar to Thursday, but warmer and with more snowfall. Look for unstable slabs on slopes over 35 degrees, particularly if they're convex or wind-loaded. The main event should occur Thursday night, so the reactivity of storm slabs may be greatest first thing in the morning. This could also be when you observe natural avalanche activity before the storm fizzles. Since we're on a warming trend, heavier snow will likely overlay softer snow, creating an upside-down snowpack. In some locations, thin melt-freeze crusts could exist below the recent snow, making for a good bed surface. As you ascend in elevation, the snow should be drier and more easily drifted into slabs by moderate to strong winds. You can use small test slopes, hand pits, or uptrack tests to gauge the slab potential of the new snow. If blocks fail easily in your tests, or you see shooting cracks during your travels, choose simpler or more treed terrain where the consequences of a slab avalanche could be less. 

    (3/18/2025) 

    A very wide but shallow crown that failed naturally the morning after a stormy night. This is in near the Thumbtack Chute, a common travel route on Chair Peak.

  • Loose Wet

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

    Below the rain/snow line, expect to find a higher potential for wet avalanches. The onset of rain on snow is predicted to occur overnight. So by the time you leave your car, the height of natural activity should be over. That doesn't mean they can't still happen. Additionally, you may be able to push wet snow on steep slopes, or snow could shed from rocky ledges or unsupported features. Luckily, this problem should be easy to diagnose. If the snow surface is sticky and wet and you're sinking in past your ankle, wet avalanches are possible, and you should head for lower-angled terrain, keeping aware of slopes above you. 

    (3/18/2025)

    Wet avalanche debris from a warm-up earlier this week. Expect similar-sized avalanches to occur anywhere fresh snow gets warm and wet.

Avalanche Discussion

We're back in a storm cycle at Snoqualmie Pass.  Observations were limited on Thursday, but it was a stormy day with new snowfall, wind, and slowly rising temperatures. That should continue overnight into Friday as a more potent storm wave impacts the zone. Unfortunately, this second wave is quite a bit warmer, and a changeover to rain is predicted at lower elevations and in the western part of the zone. Above the rain/snow line, heavy snowfall and wind are expected overnight, which could result in natural avalanche activity. Although we believe the bulk of the natural action should be wrapped up by the daylight hours, don't fully write it off. This storm should be a switch back to usual "Cascadian standards" from the low-density fluffy snow we've experienced for much of the last week. 

It's been stormy for over a week at Snoqualmie, delivering several feet of new snow, strong winds, and plenty of avalanche activity. We do not have any identified layers of concern in the upper snowpack above the atmospheric river (AR) crust, but plenty of interfaces are still visible if you dig. Some tend to fail in small column tests, particularly if graupel is involved. Recently formed wind slabs should be on the mend but are now buried below new snow and could still fail, given the proper slope. Many of this week's avalanches have failed on wind-loaded features, and we suspect if you get a deeper release, it will be in a similar location. Overall, the upper snowpack over the AR crust varies in depth based on aspect and elevation. The same goes for the number of crusts formed on sunny days. The result? Not all slopes will act the same, even if they seem similar.

Regiones cubiertas