Bollettino valanghe

West Slopes Central

Northwest Avalanche Center
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Pericolo valanghe

Sun
Alta quota
1 · Debole
Limite del bosco
1 · Debole
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

It may not take much solar radiation to thaw snow surfaces during this period of abnormally warm weather. During the heat of the day, you may encounter unstable snow in isolated areas on steep, rocky slopes in direct sunlight. If you venture high into the alpine, look carefully for evidence of wind drifted snow before committing to steeper terrain.

Problemi valanghivi

  • Loose Wet

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

    The unseasonably warm weather will continue with a fifth consecutive day of nonfreezing temperatures Saturday. Snow surfaces on steep southerly slopes may become wet and weak by midday, and another round of wet avalanche activity is not out of the question. However, sunshine and high temperatures in the 40s F will have to compete with moderate southerly winds which may keep snow surfaces firm and frozen. Wet avalanches will be most likely in steep, rocky terrain on east and south aspects above 4000ft where drier snow from Monday's storm continues to thaw. The wet loose cycle may have already run its course, but continue to watch for dripping trees, pinwheels, rollerballs, and changing conditions throughout the day. Keep an eye out for any opening glide cracks as well, and steer clear of areas near and below these unpredictable features.   

    (12/2/2020) Rollerballs and pinwheels on the east aspect of Table Mountain near 5500ft.

Avalanche Discussion

Sun and warm air (10,000-11,000ft freezing levels) significantly impacted the snowpack this week. In neighboring zones, observers reported small but widespread wet avalanche activity, even extending to northerly aspects at upper elevations. Glide cracks and small glide avalanches were reported as well in areas where thin snow cover rests on smooth rock surfaces.  The wet avalanche cycle may have peaked on Wednesday during the initial warm-up, but another round of sunshine Saturday may be enough to keep it going. A handful of natural avalanches occurred in wind-loaded upper elevation slopes during Monday's storm, but any lingering wind slabs are confined to high alpine terrain and trending toward unreactive. Although most existing cornice formations are small, they likely weakened during this dramatic warm-up and could sag or even drop onto slopes below acting as large triggers.

Snow depths throughout the west slope of the Cascades range from 40-70 inches and continuous snow begins near 2500-3000ft. Even though the current snow coverage is well above average for December (Snow Depth Climatology), early season conditions still exist. Stay alert for open creeks, tree wells, crevasses, or other exposed hazards. 

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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