Bollettino valanghe

Snoqualmie Pass

Northwest Avalanche Center
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Pericolo valanghe

Wed
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
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In sintesi

The snowpack around Snoqualmie Pass is aspect and elevation-dependent. Be on the lookout for wet avalanches on sunny slopes and dry slides on shaded ones. Avalanche size and likelihood increase as you ascend in elevation.

Problemi valanghivi

  • Loose Wet

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–1.5

    Freezing levels are expected to rise and the sun will be out. With fresh dry snow already in place from last weekend’s storm, anticipate wet loose activity to spike. This process started on Monday with snow shedding from trees and rocks. On Tuesday, instead of dribs and drabs, we could see actual avalanches - starting from a point and fanning out as they move downhill. If you see new rollerballs, fresh avalanche debris, or the surface is wet and sticky, head for shaded aspects to manage this problem.

    (12/9/2024)

    Sun-exposed slopes on the southerly end of the dial are thinner. They also produced rollerballs or snow shedding from trees and rocks.

    Photo: Andy Harrington

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–1.5

    Slabs could still fail in the recently fallen snow at mid and upper elevations. The most likely location for you to trigger one of these will be in wind-loaded terrain on the shaded half of the dial. Look for large drifts, fresh cornices, or textured surfaces near ridgelines or rocky outcrops to identify wind-loaded features to avoid. Slabs will likely be larger and potentially more sensitive as you ascend in elevation or on convex, unsupported slopes.

    (12/8/2024)

    Cracking of the snow surface in wind-drifted terrain on Mt. Snoqualmie. A red flag sign of wind slabs.

    Photo: Benjamin Pontecorvo

Avalanche Discussion

Last weekend’s storm dropped up to a foot of snow at upper elevations around the Pass, with considerably less down low. A mixed bag of precipitation types including, rain, freezing rain, and snow all fell below roughly 3400’. You’ll likely find icy and crusty snow conditions on the surface at these lower elevations.

Early-season coverage expands above roughly 3700’, and the mountains are much more winter-like. You could find that accessing these elevations is difficult, with exposed rocks, open creeks, firm crusts, and other early-season hazards. 

NWAC forecasters investigated the snowpack at 4400’ on Monday and found it is right-side up and well bonded. Although multiple melt-freeze crusts existed within the snowpack, we wouldn't currently categorize any as a layer of concern. Avalanche professionals in the Alpental Valley reported a storm interface just above the 12/7 crust failing in handpits and small column tests, but no new avalanches. The majority of avalanche activity on Tuesday, dry or wet, loose or slab, should be confined to the recent snow above the 12/7 interface. 

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