Bollettino valanghe

Olympics

Northwest Avalanche Center
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Pericolo valanghe

Mon
Alta quota
3 · Marcato
Limite del bosco
3 · Marcato
Sotto il limite
2 · Moderato
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In sintesi

Very heavy snowfall and strong to extreme winds will create large and dangerous wind slabs that you can trigger near and above the treeline. Heavy rain falling to Hurricane Ridge elevation or higher will leave near and below treeline upper snowpacks susceptible to human-triggered Wet Loose avalanches. If you find more than 6" of wet, slushy snow or 6" of fresh snow above a crust, stick to slopes less than 35 degrees.

Problemi valanghivi

  • Wind Slabs

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

    Above the recent rain/snow line, you will be able to trigger large and sensitive wind slabs on all aspects at upper elevations. Avalanche conditions will become dangerous very quickly as you ascend above a refreezing rain crust that should limit wind slab concerns below 5500-6000 ft. Professionals on Saturday reported direct evidence of a strong that a front brought heavy snow and strong to extreme winds ( full trees in motion). Winds were creating 16-20" drifts. The snowpack was struggling to adjust to the rapid loading event as indicated by 3 large settlements (whoomphs) that were heard and felt while traversing along a ridgeline at 5200. Give large slabs at upper elevation slabs a wide berth and avoid wind-loaded slopes steeper than 35 degrees. Near treeline, you may find a refreezing crust. Here, pay attention to areas where drifts are 6" or deeper and steer around these areas.

    (12/17/2020) These wind slabs formed Wednesday and fresh wind slabs will form anew on Friday.

  • Loose Wet

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

    This is likely to be the first problem you encounter on Sunday because dry snow problems are likely confined to higher elevations. We're expecting 1.3" of water equivalent to hit the snowpack with snow changing to rain overnight at lower elevations. Rain could reach as high as 6000 ft Saturday night, triggering a widespread natural avalanche cycle overnight. Precipitation should shut off by Sunday morning and the natural avalanche activity is expected to be long gone, but expect the upper snowpack may be slower to drain. Check for sticky, wet snow that you can sink in deeper than your ankle. If you find these conditions, choose slopes less than 35 degrees.

Avalanche Discussion

The weather has been very active at Hurricane Ridge. At least 4" of snow fell Saturday afternoon with rising snow levels and strong to very strong winds. 3-4 inches of fresh snow fell on Friday, following 18" of new at Maggie's storm board that fell between last Sunday and Thursday. As of Thursday, the area was just beginning to add snow to previously partially exposed southerly slopes, which now have approximately 8" above the 12/10 crust. Northerly slopes added 25-28" in wind-loaded areas. The snow came in several storms and a cooler system arriving Tuesday produced slightly weaker (less dense) snow down 16 inches that professionals found exhibited significant reactivity in slopes tests. Slightly weaker snow above the 12/10 crust yielded inconsistent results in snowpack tests, but was not believed to be a concern without significant additional loading of snow or rain. There are no layers of concern below the stout 12/10 crust.

 Travel conditions in many lower elevation areas have become challenging following a warm and wet first half of December.  Travel cautiously, particularly in forested areas where numerous obstacles lie just beneath the surface.

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.

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