Bollettino valanghe

West Slopes South

Northwest Avalanche Center
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Pericolo valanghe

Sat
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
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Non aggiornato — questo bollettino è scaduto 6 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

If you asked Santa for snow this Christmas, you might just get your wish. Look for new snow and wind to very slowly increase the avalanche danger during the day. When you see blowing snow or find deeper drifts, be leery of nearby steep slopes that could harbor wind loaded snow.

Problemi valanghivi

  • Wind Slabs

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

    Moderate winds may drift any new snow on Christmas into thin and reactive slabs on the lee sides of ridgelines and exposed slopes. Once you notice the snow accumulating, pay attention to the wind and which direction it moves the snow. Blowing snow and drifts behind objects can indicate which aspects likely hold wind slabs. If you suspect wind loading on a slope, steer around features like very steep sections and convex rollovers where you could easily trigger an avalanche. Expect potential wind slabs to be larger later in the day on the volcanoes where more snow could accumlate. Avalanches may travel on a firm smooth crust as a bed surface. This could allow them to move quickly and catch you off guard.

    (12/23/2020) Example: Blowing snow from moderate southeasterly winds was forming thin new wind slabs. Chair Peak, Snoqualmie Pass, 5200' N aspect.

Avalanche Discussion

You may find the avalanche hazard lower first thing in the morning. It will take a few hours for enough new snow to fall and blow around to slowly build any avalanche danger. Expect, the greatest danger Friday on the volcanoes where we anticipate more snow than locations closer to the Cascade Crest like Crystal and White Pass. 

A very prominent and stout crust formed last week. Currently, 4-8” (10-20cm) of recent snow sits on this icy marker (12/21). Any avalanche activity should remain above this crust layer. Last weekend we were discussing a buried persistent weaklayer in the snowpack. Several warm and rainy storms thoroughly tested this layer and several deeper avalanches were observed. You may still find this layer preserved in isolated areas, however, we don’t anticipate it being a concern in the near future. 

This crust may create challenging and slick travel conditions in some locations, especially where the wind scoured the snow down to the ice. In these spots, a simple slip could easily turn into an uncontrolled fall. Be ready for these icy patches.

Happy Holidays from your friends at NWAC!

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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