Bollettino valanghe

Snoqualmie Pass

Northwest Avalanche Center
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Pericolo valanghe

Sun
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
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Non aggiornato — questo bollettino è scaduto 5 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

A round of moderate winds may form fresh wind slabs near and below ridgelines.  Approach steep open slopes at upper elevations with caution where you find recently drifted snow.  Enjoy the deep, low density snow in more sheltered terrain to start the New Year!

Problemi valanghivi

  • Wind Slabs

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

    Moderate WNW winds may form fresh wind slabs below ridgelines overnight and Saturday.  You're most likely to trigger a slab avalanche just below lee ridges and other wind-loaded terrain features like at the base of cliffs where spin drifts have accumulated over time. If you encounter red flags like shooting cracks or recent avalanches on similar slopes, step back and choose more sheltered or simpler terrain.  

    While avalanches are likely to be shallow in depth, keep in mind that in isolated areas avalanches may break deeper to recent storm interfaces (like graupel).  

    (12/31/2021)

    Keep an eye out for wind-affected snow and signs of wind loading. These wind-textured surfaces found near ridgelines could indicate wind-loaded slopes nearby.

    Example from Crystal area. Photo: Dallas Glass

Avalanche Discussion

On Thursday, professionals noted a natural storm slab cycle near and west of the Pass.  Natural and triggered avalanches appeared to fail either at the base of the recent snow (12/29 interface) or on the graupel layer that fell during the storm (12/30).  By Friday, recent storm layers were less reactive with loose dry becoming more of an issue in very steep terrain.  Widespread surface hoar was also noted on Friday by several travelers, something to watch as we head into our next storm cycle. 

The upper snowpack now consists of several layers. The most recent (12/29) interface sits above all the cold soft snow that fell since the Solstice. While you can still discern layers in the snow above the solstice crust, we anticipate any avalanche concerns to occur near or above the 12/29 interface. On exception is a small weak sun crust that formed on 12/27. This layer only exists on steep SE-SW facing slopes. If you dig on these aspects closely inspect this layer for weak snow. 

After a slow start to winter, December has been an epic month for snow.  The WSDOT snow study plot clocks in with 181 inches (!) at 3000' for the month of December with new snow recorded every day since Dec 9th. 

Happy New Year from all of us at NWAC! 

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