Lawinenlagebericht

Snoqualmie Pass

Northwest Avalanche Center
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Lawinengefahr

Tue
Hochgebirge
3 · Erheblich
Waldgrenze
3 · Erheblich
Unterhalb
2 · Mässig
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Veraltet — dieser Lagebericht ist last year abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

A wet avalanche cycle is expected to occur Sunday night into Monday as rain falls at all elevations. Wet slides are inherently unpredictable and naturally come with a high degree of uncertainty. So build travel plans that give you a wide safety margin and consider avoiding avalanche terrain altogether.

Lawinenprobleme

  • Glide Cracks

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Likely
    Größe
    2–2.5

    We expect a natural wet avalanche cycle on Sunday night. How much activity will linger into the daylight hours becomes the question mark. Wet avalanches are impossible to predict with precision and can often occur long after the rain has stopped. As we've already seen this spring, this can even occur days after a rain event. So it's likely that wet avalanche activity will continue into the daylight hours on Monday, even as temperatures lower and upper elevations switch to snow. This includes glide, cornice falls, or blocks of snow falling from rocky ledges. You can't predict where or when these slides will happen, so your best mitigation tool will be avoidance. Avoid lingering beneath overhead hazards, such as sagging cornices or precariously hanging blocks of snow. Steer clear of large avalanche paths or slopes containing glide cracks. 

    (4/4/2025) 

    Lots of snow still clings to rocks and cliffs. Shed/glide/cornice avalanches will take center stage on Monday. Don't linger below overhead hazards such as glide cracks and cornices.

    Photo: Ian S

  • Storm Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1–2

    A general cooling trend should eventually transition upper elevations back to snow. There will also be moderate to strong winds on Monday, which could result in unstable drifts on leeward features. If you make the journey up through the rain, look for slabs on slopes over 35 degrees, particularly if they're wind-loaded, convex, or unsupported. Although a decent bond is expected with the warm and wet surface, this snow is considered weak. It could behave quite differently than you're accustomed to. You may find some sort of cross between a storm and a wet slab. Regardless of what you call it, you can manage this hazard by avoiding slopes over 35 degrees until this storm wraps up and we build a stout crust.

    (2/8/2025)

    A shallow storm slab avalanche from earlier this season. Similar slabs could develop at upper elevations on Monday.

    Photo: Bryce Bartl-Geller

Avalanche Discussion

Barring a last-minute schedule change, this is my last forecast for the season. So, it grieves me to say that I'm probably operating with the highest level of uncertainty that I've had all year. So much for going out strong. Let's hope we don't go out with a bang. Here's the deal:

Apart from the natural uncertainty that surrounds wet snow, it's unclear how much rain will enter the snowpack, at what elevations, and what types of wet slides will follow. Fluctuating freezing levels, strong winds, and multiple rounds of precipitation make it challenging to precisely pinpoint when slides could occur or even their nature. Rain is currently falling at upper elevations and will continue to do so before freezing levels slowly lower. So, even areas that seem snowy in the morning will already have free water in the snowpack.

Will that result in wet slab avalanches on top of the March AR crust? Probably at some point. Is the crust thick enough to keep rain and meltwater from this week's hot weather away from the older and weaker wet grains below? That's unclear. If water does make it through the crust into those older layers, will very large and destructive avalanches follow? Also unclear. 

What we do feel good about is that some form of wet avalanche will occur. Cornices will fail, snow will fall from rocky ledges, and loose slides will occur. Whether it's Sunday night, Monday, or even Tuesday is more challenging to determine. What we also know is that with so much weak and wet snow, if enough mass gets moving, slides can gouge down into old layers and entrain significant snow. So, although the hazard rating is considerable, you may want to consider avoiding all avalanche terrain until the storm has wrapped up.

This rain event may stick a fork in many lower-elevation slopes. It was already thin with bare ground and open creeks, particularly on sun-exposed aspects. Be cautious when traveling through this elevation band; we're swapping out avalanches for travel hazards. 

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