Bollettino valanghe

West Slopes South

Northwest Avalanche Center
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Pericolo valanghe

Tue
Alta quota
3 · Marcato
Limite del bosco
3 · Marcato
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

Stormy weather with fluctuating temperatures and strong winds will likely form new slabs that you can trigger. Steer around open area greater than 35 degrees particularly when you notice up-side-down surface snow.

Problemi valanghivi

  • Storm Slabs

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

    Stormy weather should build new slabs over the recent colder and weaker snow from the weekend. Snowfall totals and the resulting potential avalanches will be largest near the volcanoes. As a result, in these locations, you may trigger avalanches in the storm snow on any open slope greater than 35 degrees. Use uptrack and small slope tests to highlight terrain where you may trigger avalanches. Pay particular attention when you see sharp cornices, a textured surface, or see other signs of wind-affected snow. Deeper and easier to trigger avalanches will occur in wind loaded terrain. 

    For areas that receive less than 6” of snow Sunday night, keep your attention focusses on wind-affected snow. Look for drifts and blowing snow to point out which features could harbor slabs. Even though these locations may receive less snow, the danger from these avalanches is no less real.

    (3/21/2021) Uptrack tests like this can be performed by any mode of travel. They can highlight weaknesses within the new storm snow as you travel.

Avalanche Discussion

Winter-like weather has been the theme for the first few days of spring in the West-South Zone. Over the weekend many areas received 6-12” of snow, with more accumulating at Mt Rainier. This snow fell with generally cooling temperatures and moderate winds creating a soft, dry, and weak surface. As a slightly warmer storm brings additional snow to the zone, anticipate an up-side-down snowpack. You may see natural avalanches failing at this new interface, particularly during periods of heavy precipitation and/or blowing snow. While some avalanches could entrain additional snow, we don’t anticipate slides breaking into older layers. Any avalanche issues should remain above the 3/18 crust. 

Below the surface, the snowpack varies greatly by aspect. On more southerly slopes, you may find the 3/18 crust is very thick and strong. In shadier terrain, this same interface may appear as a very thin or barely noticeable crust. In all cases, a strong and well-settled upper snowpack exists. 

The recent stormy weather continues to form thin weak cornices and add to older larger ones. On Saturday, these waves of snow failed very easily in the Crystal backcountry, including several small natural collapses. Cornices often break much further back than one might expect. Give these weak features a wide berth as you travel along ridgelines. 

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