Bollettino valanghe

East Slopes South

Northwest Avalanche Center
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Pericolo valanghe

Sun
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
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Non aggiornato — questo bollettino è scaduto 4 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Slabs continue to gradually heal following a wind-loading event onto atypical aspects. Visually inspect any steep, open slopes on potentially wind-loaded aspects, steering around more continuous pillows. As temperatures warm, identify slopes 35 degrees and steeper that may destabilize with direct sunshine and move to shaded aspects.

Problemi valanghivi

  • Wind Slabs

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

    E winds drifted significant amounts of snow in the ES zone Wednesday through early Friday, forming slabs on atypical aspects. In some cases, slabs may be discontinuous as an observer found in the nearby Crystal Backcountry. In other parts of the zone, lighter winds may have hit the more optimal wind speed for slab formation. It is in these areas with more evenly distributed slabs that you really need to be on guard. You may find slabs have formed on the leeward side of ridges, under cornices, in gullies/couloirs, and cross-loading alpine features. Consider a pillow-shaped drift or textured snow surface to be guilty on a slope steeper than 35 degrees. In consequential terrain, it's not worth finding out whether the slab is innocent. Keep in mind that increasing winds on Saturday could form fresh drifts on more typical aspects. These wind drifts could form atop a variety of snow surfaces which may include crusts or very small weaker grains that may form on shaded aspects. If you find fresh slabs use simple hand pits or small test slopes to evaluate the interface.

    As you travel, use visual clues to help you identify slopes of concern. Look for textured surfaces or rounded pillows on the snow surface to determine where the wind has drifted snow. Ease into the terrain using smaller, less consequential slopes to see how the snow reacts. If you find cracks or feel firm hollow snow underneath you, step back and stay off these suspected wind-loaded areas.

    (12/3/2022)

    Actively blowing snow, freshly building sharp cornices, and textured surfaces. All easy-to-identify signs of wind-loading. Look for wind slabs on the slopes on the left side of the picture.

    Photo: Dallas Glass

  • Loose Wet

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

    Saturday will be the first above-freezing day (at lower elevations) since the cold snap and most aspects maintain cold, dry snow without a surface crust. Strong sunshine and light winds in the morning should warm steep aspects facing the direct sunshine where density snow may destabilize and fail as a fan-shaped point release. These could be wet or dry. In either case, rollerballs and snow shedding off rocks or trees should remind you to seek shaded terrain before small natural or human-triggered avalanches become concerning. Even a small avalanche may be consequential where it can push you into a depression in the terrain or over a cliff.

    Example: Rollerballs such as these will be the precursor to small loose wet slides.

     Photo: Joe Dellaporta

Avalanche Discussion

The East-South snotel sites have picked up anywhere from 3-6 inches of low-density snowfall this week. You may find the highest amounts closer to the Cascade Crest and, more specifically, close to White Pass, which did pretty well with this last system. As the winds shifted directions from west to east, this new snow easily drifted into stiff slabs for a long period of time and possibly scoured windward aspects down to the most recent crust. 

Let us know what you see by submitting a public observation. 

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