Bollettino valanghe

East Slopes North

Northwest Avalanche Center
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Pericolo valanghe

Sun
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
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In sintesi

Increasingly warm and sunny weather will result in wet avalanche activity over the weekend. When the snow surface gets wet and weak, head for shadier slopes where these unpredictable slides are less likely. Be mindful of terrain above you, where slopes could be baking in the sun and shed their winter coat.

Problemi valanghivi

  • Loose Wet

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    1–1.5

    We're entering another warm and sunny period, meaning wet avalanches should be at the forefront of your mind. On Saturday, sunshine and daytime warming will be the significant drivers in creating the conditions required for wet avalanche activity. Once the snow surface becomes wet and weak, you'll start to see rollerballs, pinwheels, and eventually wet avalanches. We expect the majority of these slides to be loose avalanches, which often start at a point near rocks or trees. They can grow large and powerful as they descend and gather snow. In some areas, they could even trigger slabs. Your best management tool will be to stick to shaded slopes to avoid these difficult to predict slides.

    In isolated locations, larger, more unpredictable shed-style avalanches could occur. Cornice collapses, glides, or even wet slabs could happen over the next few days. Keep an eye on the terrain above you, and don't linger where you see precariously hanging blocks of snow.

    (3/28/2024)

    D2 + Wet avalanche debris which released during the March 14th-20th warm-up

    Photo: Willie Webster

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–1.5

    You're most likely to trigger a slab avalanche in wind-loaded terrain on Saturday. They could be found on any aspect in the morning but may be confined to shaded slopes by day's end. As you ascend in elevation, look for visual clues such as textured surfaces, smooth pillow-like drifts, or new cornices to help identify wind-loaded features. Wind slabs commonly form in confined chutes, on convex rollovers, or near the base of cliffs/rocks. Using small test slopes can give you information about how these slabs may be reacting to your weight. If you suspect a slope is wind-loaded, choose a different route.

    (3/28/2024)

    Shooting cracks in shallow wind slab.

    Photo: Willie Webster

Avalanche Discussion

We're entering another springtime warm-up after a week of snow showers and relatively cool temperatures. It seems like we just went through a similar scenario a few weeks ago, but this time around, it shouldn't last as long or be quite as hot.

As we march into the weekend, expect dry snow problems to slowly diminish while wet avalanche problems intensify. Wet avalanches are notoriously challenging to forecast peak instability, and the problems can be intermingled. We could see the mountains start to fall apart on Saturday, or it may not happen until Monday or Tuesday. So stay vigilant and know that it's likely coming at some point over the next few days. 

We anticipate most avalanche activity to occur in the snow above the 3/22 melt-freeze crust. Observations from the eastern part of the zone indicate that this interface varied in thickness with elevation, diminishing above ~6500'. Where the 3/22 is stout, it could make a good sliding surface for loose avalanches to run on and gather mass as they descend.

The major uncertainty with this warm-up revolves around the activation of older, persistent weak layers. We recently removed this issue from the official problem list, thinking they are dormant. However, observations indicate that the structure still exists in isolated locations. There have been no indicators of instability, such as recent avalanches. However, a widespread avalanche cycle occurred on these layers last time we had a significant warm-up. If you want to minimize your exposure, make travel plans limiting time spent in large, complex, and unsupported start zones. This layer may be more active in high-elevation northerly terrain or areas further east in the zone, such as the Pasayten or Harts Pass.

Snowpack information is limited. Let us know what you find if you get out into the backcountry!

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