Bollettino valanghe

Olympics

Northwest Avalanche Center
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Pericolo valanghe

Sat
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
2 · Moderato
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Non aggiornato — questo bollettino è scaduto 5 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Avalanche danger will rise in the alpine as wind builds new slabs and drifts. You may be able to trigger small to large avalanches along and near ridgelines later in the day. Expect surface conditions to vary by aspect and continue to use an abundance of caution around and below cornices.

Problemi valanghivi

  • Wind Slabs

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

    Light to moderate snow showers and a cooling trend bring 6-10 inches of new snow by Friday evening. The timing on this snow is uncertain -- expect a couple inches overnight, then more off and on through the day on Friday. Less snow means less avalanche danger. The danger will be much lower if the snow forecast does not verify, or if the winds don’t blow.  

    Moderate winds (15-25mph along ridgelines) will create dense slabs along and near ridgelines in places where there is more than 6 inches of new snow. These slabs may, or may not be easy for a human to trigger. The old snow surface is highly variable; the new snow may bond well to some surfaces and not so well to others. 

    Test the interface between the new and old snow before committing to consequential routes. Avoid steep unsupported slopes where the new slabs are more than a foot deep and are markedly more dense than non-wind affected snow.

    Example of the type of avalanche you may encounter by Friday afternoon. Avoid wind-loaded upper elevation start zones as the storm progresses, especially if they are connected to a cornice. Photo: Jere Burell

Avalanche Discussion

Recent mild weather created a strong crust on solar slopes and light faceted snow on shady slopes. Light precipitation during the day Thursday probably didn’t change conditions all that much. 

The weather forecast is calling for increased winds, cooling air temperatures, and a couple inches of new snow. There is a break in the precipitation overnight, then scattered showers through the day tomorrow. New snow behaves differently when it falls on different surfaces. The old snow surface is quite variable -- firm crusts on the southerly slopes, light faceted powder on the northerly slopes, and breakable crust on the west and east slopes.  The take-home is that avalanche conditions may change significantly depending upon what aspect and elevation you are on. 

For example, I expect the new snow to be well bonded to the old snow surface at lower elevations and on non-wind loaded slopes, but it may be touchy in areas where wind is building new slabs on old crusts or surface facets. Take the time to assess the new snow stability when you change aspects and pay attention to cracking, collapsing, and rapid changes in snow density as you travel.

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