Bollettino valanghe

Olympics

Northwest Avalanche Center
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Pericolo valanghe

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

Easily triggered small, inconsequential avalanches are growing to the point they could ruin your day. That transition will happen more rapidly above treeline. Stick to slopes less than 35 degrees where you find 6" or more of snow above the stout crust.

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–2

    Moderate SSW winds and light amounts of new snow falling Friday night and Saturday morning will add to existing wind slabs, primarily on northerly aspects. Wind slabs will grow larger and become increasingly sensitive to trigger as you ascend in the terrain on Friday. Expect to easily trigger wind-loaded terrain features as you approach ridgelines and above treeline terrain. Slabs may fail within new snow and may step down to a weak interface above the 1/13 crust and likely bed surface.  They could initiate on surface hoar if buried Friday night. Look for signs of active snow loading including blowing snow, fresh cornices, and textured snow surfaces.  Avoid all wind-loaded slopes steeper than 35 degrees where you find 6" or more of snow above the stout crust. 

    Wind-drifted snow will be the critical ingredient necessary for more dangerous wind slabs on Saturday.

Avalanche Discussion

On  Thursday and Friday, Professionals easily triggered 4-6" wind slabs in specific terrain features and shallow loose dry avalanches running on at stout crust. They found recent low-density snow averaging 2-4". Light to moderate sustained SSW ridgetop winds Tuesday through Wednesday morning transported the snow into 6-8" wind drifts. These drifts initiated from a density change within the wind slabs.   The new snow and drifts lie over weak snow (facets) just above the stout 1/13 rain crust. On a NE aspect, observers found a thin temperature crust within the weak snow. Weather inputs have been minimal over the past 48 hours with cool temperatures and light winds, although the winds were just enough to transport a small amount of snow above treeline on Friday.

A layer of large-grained surface hoar stuck around on W-N-E aspects below ridgelines on Friday and we'll need to watch to see whether this layer gets buried.

While wind slabs should be your primary focus, in less wind-affected areas, you can initiate a loose dry avalanche on slopes approaching 40 degrees and steeper. Remind yourself of the increased risk of injury associated with any avalanche involving a stout crust near the surface.

Despite the recent snow, wind transport of snow from southerly to northerly aspects has exposed icy slopes, and patches of bare ground. Make sure you can safely arrest a fall before crossing icy slopes.  

2020-21 Forecast Schedule: Avalanche danger ratings will be issued for the Olympics every Friday through Sunday and during mid-week holidays. During the week when the Hurricane Ridge road is closed, forecast information will be updated daily to include expected conditions and relevant travel advice under the No Rating label.

During the ongoing Covid-19 pandemic, continue to follow the latest guidance from local, state, and federal health officials. Avoid unnecessary risks that could impact first responders and stress medical resources.  Wear a mask when appropriate, practice social distancing, and consider recreating closer to home.

Regioni coperte