Bollettino valanghe

East Slopes North

Northwest Avalanche Center
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Pericolo valanghe

Wed
Alta quota
4 · Forte
Limite del bosco
4 · Forte
Sotto il limite
3 · Marcato
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In sintesi

Expect very dangerous avalanche conditions on Tuesday. Strong to extreme winds, heavy snowfall, and weak layers in the snowpack are a recipe for large avalanches. Avalanches could break widely and run naturally from overhead. Avoid traveling on or under steep slopes until this storm plays out.

Problemi valanghivi

  • Storm Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Very Likely
    Dimensione
    2–3

    Tuesday won't be a day to venture into avalanche terrain. Natural and human-triggered storm slab avalanches will be widespread. Avalanches could measure 2-4 feet deep and propagate widely across terrain features. Avoid traveling on or under slopes greater than 30 degrees, particularly at middle and upper elevations where avalanches will likely be much larger. At lower elevations with a thinner snowpack, avalanches might be smaller, but they would carry high consequences if you are dragged through terrain still riddled with rocks, stumps, creeks, and other terrain traps. Strong to extreme winds will drift snow into thicker slabs, where you could trigger a stiff wind slab avalanche. With these high wind speeds, finding sheltered slopes that lack significant wind drifting may be challenging. 

    If you venture out into the blizzard-like conditions for winter recreation, be sure to find sheltered, low-angle slopes not exposed to overhead hazards from steep slopes above. It will be a great day to observe red flag signs of instability, like collapses and shooting cracks, from low-angle terrain.

    (1/7/2024)

    Even with little new snow, a natural wind slab occurred between 1/6-1/7 near Harts Pass. While we don't know what layers were involved in this slide, it is a bullseye sign of unstable snow. 

    Photo: Jason Davis

Avalanche Discussion

If you venture out into the blizzard-like conditions for winter recreation, be sure to find sheltered, low-angle slopes not exposed to overhead hazards from steep slopes above. It will be a great day to observe red flag signs of instability, like collapses and shooting cracks, from low-angle terrain.

Expect blizzard-like conditions in the mountains on Tuesday with heavy precipitation, warming temperatures, and winds up to 50mph. Avalanche danger will increase rapidly on Tuesday night, and we expect natural activity to continue into the day. This storm will overload the various weak layers that developed during the prolonged dry(ish) period in the Eastern Cascades. Lower elevations hold less snow and, in many places, do not have the threshold for large avalanches. However, we still expect smaller avalanches at lower elevations, and these could carry serious consequences with the additional terrain traps still protruding from the thin snow cover."Weak and variable" sums up the snowpack around the zone. There are several decomposing crusts and layers of sugary facets. In some locations, these layers present as individual prominent bands; in others, they all meld together. NWAC staff near Cutthroat Lake today found near-surface facets forming throughout the terrain, and crusts with weak, faceted snow below and above failed on isolation in snowpack tests on Sunday. This weak snowpack structure, combined with heavy precipitation and winds, will likely lead to a widespread natural avalanche cycle, and these slides have the potential to break widely across the terrain in surprising ways. Even with the recent snow, coverage remains thin, particularly at lower elevations. Open creeks, rocks, logs, and bushes continue to make travel more difficult than we're used to for this time of year. 

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