Bollettino valanghe

Snoqualmie Pass

Northwest Avalanche Center
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Pericolo valanghe

Fri
Alta quota
2 · Moderato
Limite del bosco
1 · Debole
Sotto il limite
1 · Debole
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Non aggiornato — questo bollettino è scaduto 3 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

You're most likely to trigger an avalanche in a pocket of wind-drifted snow at upper elevations. Fresh cornices, textured surfaces, or large drifts are clues to help you identify wind-loaded features to avoid. Before committing to consequential terrain, take the time to dig in the upper snowpack to look for weak crusts that could pose an issue.

Problemi valanghivi

  • Wind Slabs

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

    You could find shallow wind slabs on a variety of aspects on Thursday. The wind direction has been shifting as several waves of precipitation have reached the Pass this week. Slabs may have developed on aspects you’re not accustomed to. Look for fresh cornices, drifts behind objects, or textured surfaces to help determine which way the wind was blowing and thus wind-loaded slopes. Cracking of the snow surface or fat pillow-like drifts are signs that you’ve found a wind slab, and you should retreat to lower-angled terrain. They’ll be more likely near rocky features or ridgelines.

    (12/27/2023)

    Very small natural wind slab crown seen around 4600 ft on Draft Dodger Ridge. 

    Photo: Caya Johnson

Avalanche Discussion

NWAC forecasters were out with their interns around the Snoqualmie Pass zone on Wednesday. A similar snowpack structure was discovered by both teams - in the Alpental Valley and in the eastern part of the zone. Snow height increases dramatically as you travel through the middle elevation band. A crust capped the snowpack up to at least 5000'. Below it, dry snow existed with two major crusts in the upper 1.5 feet - the 12/22 and the 12/25 interfaces. Although not of high concern yet, these interfaces look like they may be trouble if we get a good snow load on top of them. They both produced easy snowpack test results and consisted of crusts sandwiching weak snow. You may want to examine these layers before jumping into consequential terrain in the coming days. 

Apart from the snowpack structure, winds were seen sifting snow to the base of cliffs and near ridgelines, and open creeks still abound. A few tiny avalanches were observed.

Thursday will be a bit like Groundhog Day, with some gusty winds and light precipitation of either snow, drizzle, or freezing rain, depending on elevation. Hopefully, skies will begin to clear in the afternoon. You'll likely need to get above the elevation of Wednesday's surface crust in order to find snow available for transport to create new wind slabs.

Continue to take care to avoid open creeks and holes or exposed rocks and logs while traveling in the mountains. 

Regioni coperte