Bollettino valanghe

West Slopes North

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

Although December brings short days and weak solar radiation, the heat on Friday will be enough to weaken snow surfaces and maintain concern for wet loose avalanches. Monitor steep sun-exposed slopes and changing conditions with aspect and elevation. Unstable areas of wind drifted snow from Monday's storm may still linger in isolated terrain features high in the alpine.

Problemi valanghivi

  • Loose Wet

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

    Above freezing temperatures will continue for a third consecutive night Thursday, while Friday will bring another round of sunshine with highs in the 40's F in the mountains. You may encounter wet and weak snow surfaces on any aspect, but wet avalanches will be most likely on steep, rocky slopes in direct sunlight. Be especially cautious mid morning through early afternoon on south and east aspects above 4000ft where drier snow from Monday's storm continues to thaw. Watch for dripping trees, pinwheels, and rollerballs as clues that loose wet avalanches may follow. Wet avalanches could entrain significant snow as they run downslope and may even grow large. Pay attention to changing conditions throughout the day, and move to shaded or lower angle terrain to avoid the problem. Watch 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.

  • Wind Slabs

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

    Snow from Monday's storm was redistributed by strong southerly winds, and evidence of previous wind loading is easy to find high in the alpine. Even though wind slabs are a few days old and gaining strength, pay attention as you climb up in elevation and transition into wind affected terrain. Watch for blowing snow, lens-shaped pillows, and sudden changes in snow surface texture and hardness. Steer around steep slopes and large convex rollovers where you see old large drifts or feel firm hollow snow. Also, keep in mind that cornices may weaken during this dramatic warm-up and could sag or even drop onto slopes below acting as large triggers.

    (12/2/2020) Looking towards Ptarmagin Ridge and the NE side of Mt. Baker from Artist Point. Plenty of evidence of wind drifted snow in the Alpine.

Avalanche Discussion

Recent sun and warm air (10,000-11,000ft freezing levels) have had a significant impact on the snowpack. Concern for wet avalanches will continue until cooler weather allows snow surfaces to refreeze. Wet avalanches since Wednesday have generally been small (D1.5) but widespread, even extending to northeast 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.  A handful of natural avalanches occurred in wind-loaded upper elevation slopes during Monday's storm, but lingering wind slabs becoming harder to trigger.

Snow depths range from 40-70 inches in the Mt. Baker area, and continuous snow begins near 2500-3000ft. Even though snow coverage is well above average for this time of year (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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