Bulletin d’avalanche

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Northwest Avalanche Center
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Danger d’avalanche

Mon
Alpin
3 · Marqué
Limite forestière
3 · Marqué
Sous la limite
3 · Marqué
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Périmé — ce bulletin a expiré 2 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

Although we're past the peak danger, avalanche terrain remains unsafe for travel. Rainwater continues to move through a recently dry snowpack and large natural avalanches may continue to fail without warning. Seek non-avalanche terrain until the snowpack has a chance to refreeze or more fully drain.

Problèmes avalancheux

  • Wet Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    2–2.5

    Typically when heavy rainfall saturates a previously dry snowpack, most of the natural avalanche activity occurs with that initial change. However, some avalanche activity will occur as rainwater percolates deeper into the snowpack and lubricates crusts and weak layers deeper in the snowpack. We remain concerned about weaknesses in the snowpack formed during the January Drought. Wet slabs are notoriously unpredictable. Continue to stay safe by avoiding areas where avalanches can start, stop, or run. Wet avalanches might also just fail as loose wet avalanches such as the one pictured in the gallery below.

    Example: A large natural wet avalanche like we expect to see Saturday and Sunday.

    Photo: Rob Pollard

  • Storm Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    1–2

    Cooling temperatures will bring snow levels back to middle elevations on Saturday morning before warming raises snow levels in the afternoon. We're expecting enough snowfall at upper elevations for a storm slab problem. You can trigger one of these on a steep slope where you find 8" or more of fresh snow. The snow may be heavy, wet and could entrain the snow easily on the slope below, making it difficult to escape unscathed.

    (2/1/2025)

    An intentionally triggered small storm slab. 3-12" deep, and 20 feet wide. SS-ASc-D1-R2-S, NE, 6200ft

    Photo: Dallas Glass

Avalanche Discussion

Prior to this warm, wet storm shaded aspects hosted variable snow surfaces (a mix of shallow wind slabs and thin surface crusts), but the upper snowpack will look very different, with over an inch of liquid rainwater impacting the snowpack by Sunday. You will find some fresh images of the driving rain and soggy conditions in the Hurricane Ridge area on Saturday in the gallery. South-facing slopes are losing significant snow coverage.

We're expecting a relative lull in the deluge with some cooling late Saturday night into Sunday morning. This will help decrease the avalanche danger, but more rainfall and warming may cause further snowpack deterioration in the afternoon.

We removed the January Drought Layer (JDL) and associated crust complex as a problem, but we think it could reactivate this weekend Sunday. Facets are sandwiched between a series of crusts (1/10 and 1/29) 16-20" below the snow surface on shaded aspects. Rainwater will pool and destroy these weaker snow grains causing large (or very large) slab failures. 

Share your observations with the community and NWAC. Even if you didn't see an avalanche or a snowpack test, your information is incredibly valuable.  Every afternoon, 4-5 NWAC forecasters from around the region meet to discuss the latest snowpack and avalanche observations, and weather forecast to create the next day's avalanche forecast.  We look at information from the public, other snow professionals, and weather station data to round out our picture.  Share early and often!

Régions couvertes