Boletín de aludes

East Slopes North

Northwest Avalanche Center
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Peligro de aludes

Sun
Alta montaña
3 · Notable
Límite del bosque
3 · Notable
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

Despite the sunshine, Saturday will be dangerous and it will be a day to avoid slopes over 30 degrees on the north half of the compass. Deep and widely propagating avalanches are likely on an older weak layer 2-3 feet below the surface. If you find wet snow on sunny slopes, move to lower-angle terrain and avoid lingering beneath cornices.

Problemas de aludes

  • Wind Slabs

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

    Recent winds formed wind slabs on lee slopes at mid and upper elevations.  These slabs are likely gaining strength, but you could still trigger one in steep, unsupported terrain or confined rocky features. Triggering a smaller wind slab avalanche could initiate a much larger avalanche on older, weak snow.  Avalanches on these deeper layers may be more likely from large triggers such as cornice falls. 

    (2/6/2025)

    This large (D2) slab avalanche was likely triggered by cornice fall. Estimated crown depth is 1.5-2ft. Liberty Bowl, NNW, 7,200ft

    Photo: NCMG

  • Persistent Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Likely
    Tamaño
    2–3

    Tread carefully and put a large buffer between where you travel and steep slopes. Choose more conservative terrain than normal. Warming temperatures will keep these avalanches reactive, and you could trigger them from below or on adjacent to steep slopes. 

    Since the 26th, there have been multiple reports of widely propagating avalanches. Three backcountry riders have been buried in two separate avalanches near Harts Pass and one person was killed. More info in the Forecast Discussion.  With the January Drought Layer (JDL) nearly 3ft deep now, you may not receive warning signs of whumpfs or collapses in flatter terrain. Avalanches may run full path into flat terrain below. The only way to manage these problems is avoidance. Make conservative route selections and avoid overhead exposure from cornice failures and steep, northerly terrain.

     

    (2/28/2025)

    A large avalanche near Hart's Pass that caught 2 snowmobilers and resulted in one fatality on February 28th. 

    HS-AM-D2.5-R4-O. Cone Mtn, NE, 6,800ft

    Photo: NCH

  • Loose Wet

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

    Once surface crusts melt, directly sun-exposed slopes on southeast through southwest aspects could be wet and unsupportive.  Wet avalanches will be possible on more shaded terrain. Move to lower-angle slopes if you see rollerballs or fresh avalanches. Be aware of avalanches coming from overhead terrain. They may run naturally from above. 

    Consider the consequences of a large glide avalanche or cornice fall. While these may be less likely, the consequences could be severe. Avoid lingering underneath glide cracks, cliffs, or overhung cornices. These overhead hazards run naturally and could trigger an avalanche on slopes below.

    (2/27/2025) Natural wet avalanches off of Cutthroat Peak from the recent warming.

     Photo: Ryan Minton

Avalanche Discussion

Preliminary Report: On Friday, February 28, three snowmobilers were riding near Harts Pass in the East North zone when they triggered a large slab avalanche. Two riders were caught and carried. One rider was fully buried and killed. The other was partially buried and injured. NWAC is working with local avalanche professionals to conduct an investigation. Our deepest condolences to the family, friends, and community. (NE, 6,800ft HS-AM-D2.5-R4-O)

As we continue this spring-like weather, expect variability and aspect-dependent surface conditions. You'll likely find breakable crusts of varying thickness on west, south, and east aspects and dry snow on northern slopes at upper elevations. We expect that with warmer temperatures, surface crusts will break down quickly. Plan your day so you can move off of and out from under steep sunny terrain by early afternoon. 

This week, avalanche professionals reported several very large persistent slab avalanches throughout the terrain. Observers near the avalanche incident on Hart's Pass (see above description in the Persistent Slab Problem) also reported other widely propagating avalanches in steep, rocky terrain. These avalanches likely failed on the January Drought Layer (JDL), now 2-3' below the surface.  Earlier this week, travelers near Cutthroat Creek and Silverstar felt several collapses. We have been concerned about these types of avalanches for the better part of February. But, it wasn't until the recent warm snowfall formed a more substantial slab over the JDL that we began to see increased reactivity. But now that we have a cohesive slab, this problem might not heal quickly. So, patience and conservative decisions to avoid steep, northerly terrain are essential to avoid triggering one of these massive avalanches. 

Heavy, dense snow layering over weak faceted snow in the foothills near the Methow Valley led to reports of whumfping and small avalanches the last 2 days.  We expect the prolonged warm temperatures will eventually help strengthen this weak snowpack structure, but this problem should still be on your radar until we get a solid cold night with a good re-freeze of the snowpack.

You can help us gather more data by submitting an observation HERE or via the Avy App. 

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