Bollettino valanghe

Snoqualmie Pass

Northwest Avalanche Center
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Pericolo valanghe

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

In many locations, you will likely find soft unconsolidated snow that may only result in small sluffs. However, if you travel into more exposed areas, look for subtle clues that the wind turned this soft snow into a slightly firmer slab. Textured surfaces and small drifts can point out slopes you want to avoid.

Problemi valanghivi

  • Wind Slabs

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

    While most of the snow surface around Snoqualmie Pass is soft and unconsolidated, you want to keep your eye out for areas where the wind turned this soft snow into a potential problem. If you’re going to trigger a slab avalanche, it will most likely be in wind drifted snow along a ridgeline, exposed slope, or the base of a cliff. Look for blowing snow, cornices, and drifts to figure out which aspects and features might hold potential wind slabs. 

    Ridgetop winds at the Pass continue to shift back and forth from West to East. As a result, you could find wind slabs in some locations you don’t normally expect. While we don’t anticipate this problem to be widespread, ample soft snow and moderate winds will keep this issue on our minds.

    (12/13/2021)

    Example: Sharp cornices and smooth snow pillows indicate wind loading on this slope. 

    Photo: Robin Pendry

Avalanche Discussion

While Snoqualmie Pass isn’t expected to get a significant amount of snow Wednesday, nearly a week’s worth of storms quickly turned the mountains into winter. More than 3 feet of snow fell at Pass level, with even more at higher elevations. You can still find several storm layers in the upper snowpack. Some of these even produced small storm slab avalanches as recently as 12/12. However, most observations indicate a generally right-side-up snowpack. One layer we continue to track is a thin crust (12/8) about 4-6” above the icy block at the bottom of the snow. In nearby Stevens Pass and the West South zones, small weak facets were observed near this crust. So far, we have not confirmed any avalanches on this layer. However, if you dig in the snow, see if your snowpack tests fail suddenly or slide easily on weak grains around the crust.

Even with all the new snow, the snowpack is relatively variable and can change by aspect, elevation, and location. It’s this uncertainty that has our attention. Consider using smaller low consequence slopes to gather information before stepping out into larger and less forgiving terrain. 

Open creeks continue to present a barrier to backcountry travelers. Choose your travel routes and creek crossing carefully.

Regioni coperte