Bulletin d’avalanche

Olympics

Northwest Avalanche Center
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Danger d’avalanche

Sat
Alpin
2 · Modéré
Limite forestière
2 · Modéré
Sous la limite
1 · Faible
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Périmé — ce bulletin a expiré 4 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

While the overnight snow totals might not catch your attention, they should be enough to build a fresh round of slabs on wind-loaded slopes. Watch out for pillow-like drifts on the lee sides of ridges, below cliffs, and in the tops of chutes. Steer around wind-loaded terrain by using lower angled or less wind-affected slopes.

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1–1.5

    Moderate to strong winds out of the SW should easily build a new batch of wind slabs you’ll need to navigate on Friday. In many ways, this is your normal wind slab day, but two things make this round a little unique. 

    1. These slabs will likely sit on a newly formed crust. This could allow them to fail easily and travel quickly.
    2. As winds decrease, a dusting of soft snow may hide some of the more obvious wind slab clues. So, you’ll need to keep a keen eye out to anticipate and avoid wind-loaded slopes. 

    Look for scoured areas, fresh cornices, and sharp drifts to figure out where these wind slabs may exist. Because they will be a little hidden, you may need to give wind-loaded areas a bit more space. While these slides should remain small, some of them could grow large enough to knock you off your feet or flush you down a chute.

    (2/9/2023)

    Cornices and scoured slopes are great clues to help you anticipate possible wind loaded slopes. 

    Photo: Sam Siemens-Luthy

  • Loose Wet

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1

    We’ve reached that time of year when sunshine following a storm generally results in natural loose wet avalanches. This problem might not happen, but we think the skies will clear enough to allow the sun and warm temperatures to cause rollerballs and small point release avalanches on steep southerly slopes. These slides will likely be the most problematic in the near treeline band where enough new snow exists to produce legitimate avalanches. Don’t let this easy to anticipate and manage issue catch you by surprise and push you into a creek or over a cliff.

    (2/9/2023)

    This natural loose wet avalanche occurred during Thursday's (2/9) sunny and warm weather. 

    Photo: Sam Siemens-Luthy

Avalanche Discussion

By Friday morning, the bulk of the storm will have passed the Olympics. That means these newly formed slabs will be the most reactive right out of the gate. As the day progresses you may see them become harder to trigger. Conversely, if the sun comes out, you could encounter an uptick in wet avalanche concerns.

Besides the sky, the other big question mark is a layer of weak snow buried in the upper snowpack (2/3 interface). NWAC Pro Observer and NPS rangers on Thursday routinely found a crust/facet layer about 2 ft (60cm) below the snow surface on northerly aspects. Given the current snowpack structure, it seems unlikely that you will trigger a slide on this layer. However, a larger trigger (another avalanche) or the wrong piece of terrain (rocky complex slopes) could result in a deeper and more consequential avalanche. 

Today’s observations also reported a newly forming breakable surface crust on all aspects up to at least 6000 ft. This layer correlated well to warm temperatures at upper elevations and trees/rocks shedding snow. Thursday’s warm-up even resulted in several natural loose wet avalanches.

Régions couvertes