Boletín de aludes

East Slopes South

Northwest 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 4 years ago. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

Lingering pockets of unstable wind drifted snow and wet avalanches are the primary concerns for Monday. Avoid stiff, pillow like drifts of snow along ridges and steep wind-exposed terrain. On sunny slopes, don't linger underneath steep, rocky terrain where wet avalanches are more likely to initiate. 

Problemas de aludes

  • Wind Slabs

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

    Recent snow with strong winds likely built stiff slabs of wind driven snow on the lee side of ridgelines, at the base of cliffs, and on steep rollovers in exposed terrain. Most of these should be small and possibly stubborn to trigger. However, as you ascend in elevation, avalanches are likely to be larger and remain more sensitive to triggering. Look for smooth pillow-like drifts, textured surfaces, and cornices along ridgelines to identify probable wind slab locations. Before committing to steep slopes in wind exposed areas, look for signs of instability in small test slopes, such as long shooting cracks. Upside-down snow is also a great sign that you have found a wind slab. Steer around these stiff drifts of snow where they exist on slopes greater than 35 degrees. 

    (12/3/2022)

    Shooting cracks like this are in-your-face indicators pointing at unstable snow. Move to lower angled and more sheltered slopes  if you see signs like this.  

    Photo: Dallas Glass

  • Loose Wet

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

    On Monday, it will be a sunny, warm day in the East South zone, and this fresh snow will be particularly sensitive to sun and warming. So a healthy dose of sunshine along with warming temperatures will likely lead to wet loose avalanches in steep, sunny slopes. Cliffs, rocks, and tree bombs are often where these avalanches initiate from, so be aware of overhead hazard from steep sunny terrain. If you feel the snow beneath you becoming sticky with wet surfaces in the sun, move to lower angle or shadier terrain. 

    (12/3/2022)

    If you see rollerballs, these are signs that the snow surface is becoming wet and weak. 

    Photo: Zack McGill- Cascade Mtn Ascents

Avalanche Discussion

Before this storm, clear and cold nights most likely created weak surfaces with facets and surface hoar. We don't have many observations from the zone, but these weak snow layers were common throughout the rest of the east slopes of the Cascades. This may have created a poor bond between the old snow and the recent storm snow. The strong winds associated with this storm may have destroyed these layers in some more exposed locations and left them intact in others. So while wind slabs are the primary concern, you should also monitor this recent interface. Before stepping out into more committing or steep terrain on Monday, take a minute to check the bonding of the new snow to the old surface to see if it fails easily wherever you're recreating. Use quick hand pits and small test slopes to observe how the recent snow reacts. Slopes with a weak interface between the old and new snow layer could break wider than anticipated.

Chances are you will encounter challenging travel across the zone on a stout rain crust from mid-January, just below recent new snow. You may find shallow conditions at lower elevations with many hidden hazards, like exposed or barely covered rocks or stumps.  

If you get into the East-South, please let us know what you see by submitting a public observation! 

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