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
2 · Moderato
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In sintesi

You can trigger a slab avalanche on either side of the ridgelines, with the largest and most dangerous slabs at upper elevations. A reactive density interface that produced several human-triggered avalanches on Friday may remain reactive at lower elevations on Saturday. Dangerous conditions exist at all elevations for the eastern Olympics where we expect 1-1.5 ft of snow. Avoid all slopes steeper than 35 degrees if you travel in this terrain.

Problemi valanghivi

  • Wind Slabs

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

    Much of the snow in the Olympics has settled in a right-side-up manner, making for great riding conditions. However, wind-affected snow where it exists will form the slab needed for a more consequential avalanche on Saturday. Below treeline, you might find a wind-affected density interface that was responsible for two small human-triggered avalanches on steep or unsupported terrain below treeline on Friday. We think these sort of avalanches will become isolated below treeline by Saturday. However, as another round of moderate winds moves through early Saturday, expect more reactive and dangerous slabs to form near ridgelines with some larger slabs possible in more heavily wind-exposed or alpine terrain features. Shifting winds may form reactive slabs on either or both sides of a ridgeline. Visual clues such as rounded snow pillows may help you identify areas to avoid.  A naturally triggered wind slab on Thursday serves as a strong reminder near ridgelines, winds can form reactive slabs quickly within drifted low-density snow. Settlement of the snow as you travel and shooting cracks serve as a reminder that you're entering wind affected or wind loaded terrain where you'll want to keep your slope angle under 35 degrees.

     

    (3/2/2023)

    Shifting winds may form wind loading on both or either side of ridgelines.  Monitor for rounded pillow-like drifts on both sides of the ridge.

    Photo: Sam Siemens-Luthy

  • Loose Dry

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

    Small dry loose avalanches were moving quickly in steep, wind-protected terrain on Thursday and Friday. Expect surface snow to destabilize and move with you in terrain approaching 40 degrees or steeper. These avalanches warrant greater caution above cliffs, depressions in the terrain, or rocks.

     

    Example: A small dry loose avalanche, or sluff,

    Photo: Irene Henninger

Avalanche Discussion

IF YOU'RE TRAVELING IN THE SOUTHERN OR EASTERN OLYMPICS: Expect higher than forecast avalanche danger with storm and wind slabs producing dangerous avalanche conditions at all elevations. Large human-triggered avalanches are expected to be easy to trigger. Avoid steep, open slopes at all elevations.

At Hurricane Ridge, another 4" of low-density snow fell on Friday with light winds, adding to around 6" of snow fell on Thursday. We're now up to nearly 2 ft of right-side-up snow above the 1 cm 2/20 crust. We're monitoring a layer of slightly faceted snow just beneath the 2/20 crust. Although we don't believe this is a current cause for concern, it's always worth keeping an eye out for evidence to the contrary. If you hear whumphs or settlement, this layer may be problematic in your area. Likewise, if you experience more widespread slab formation due to higher-than-expected snowfall rates or graupel, dial back your terrain selection to exclude all slopes steeper than 35 degrees. Snow coverage is currently excellent with forests now filled in above 4500 ft.

The photo gallery shows a natural avalanche (from Thursday) and two human-triggered avalanches on Friday, all of which would be large enough to ruin your day in higher-consequence terrain. 

 

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