Boletín de aludes

East Slopes North

Northwest Avalanche Center
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Peligro de aludes

Sat
Alta montaña
1 · Débil
Límite del bosque
1 · Débil
Bajo el límite
1 · Débil
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Desactualizado: este boletín caducó 4 years ago. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

Avalanches are generally unlikely. However, in the afternoon, you may be able to trigger small wet avalanches in isolated, very steep terrain near rocks and cliffs. Don't linger underneath cornices and travel cautiously in extreme terrain where even small avalanches can cause falls with high consequences. 

Problemas de aludes

  • Loose Wet

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Unlikely
    Tamaño
    1–1.5

    The snowpack is likely adjusting to the warm temperatures and trending towards a diurnal spring melt-freeze cycle. On Wednesday, cold overnight temperatures resulted in a solid refreeze of the upper snowpack and decreased the likelihood of wet loose avalanches. However, as the day warms up on Friday, small wet loose avalanches may become a concern in very steep terrain. The daily temperature fluctuations in the springtime are more significant than earlier in the winter. A cold night with a good refreeze of the snow surface can decrease the likelihood of wet avalanches the following day as the temperatures climb back to well above freezing. So, take note of how well the snow surface when you start your day. Wet avalanches will be more likely as the day warms if you easily punch through a surface crust in the morning. If the snow surface is well frozen and supportable in the morning, wet avalanches are less likely as the day warms. You should still look for signs of wet loose avalanches such as rollerballs and fresh fan-shaped avalanches, and if you begin to sink deeply into wet, heavy snow, it is best to stick to lower angle slopes. Even though the expected size is relatively small, keep in mind that even small avalanches can have high consequences in extreme terrain.

    Any large cornice falls could be dangerous in their own right, and they could also trigger deeper avalanches below. Attempt to minimize your time underneath lingering under large overhung cornices, and don't be afraid to steer widely around potential runout zones. Some shaded, northerly aspects near and above treeline may still harbor more deeply buried faceted layers. Large triggers, such as cornices, could initiate deeper slab avalanches on these layers.

    (3/22/2022)

    Large (D1.5) wet loose avalanche in one of the main Cutthroat paths above Hwy 20.

    Photo: Andy Harrington

Avalanche Discussion

A widespread natural wet loose avalanche cycle occurred on Tuesday near Washington Pass. On wind-sheltered NW-NE aspects near and above treeline, observers found near-surface facets 1-2 feet below the surface and often on a crust. This layer was the source of persistent slab avalanches near the Mount Baker ski area and other parts of the Cascades. A layered, winter snowpack still exists on these higher elevation northerly aspects. So even though the avalanche danger is low, dig down to identify any weak snowpack structure before committing to steep terrain. 

A deeper persistent weak layer still exists in the zone. The layer can still be found about 3 feet deep, sandwiched between eroding crusts on NW-NE aspects near and above treeline and has been particularly problematic in the Harts Pass area. The most recent of these occurred on March 9th in Allen Basin. While triggering an avalanche on this layer (the late January facets) is unlikely, the consequences could be serious. You can limit your exposure to shallow, rocky areas and steep and unsupported slopes. After a widespread avalanche cycle on 2/28-3/1, observers reported several deep crowns and avalanches throughout the zone that likely ran on the weak layer. See the avalanche occurrence database for more details.

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