Lawinenlagebericht

Snoqualmie Pass

Northwest Avalanche Center
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Lawinengefahr

Wed
Hochgebirge
4 · Gross
Waldgrenze
4 · Gross
Unterhalb
3 · Erheblich
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Veraltet — dieser Lagebericht ist 3 years ago abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

Heavy precipitation, very strong winds, fluctuating temperatures, and weaklayers in the snowpack all add up to one thing: very dangerous avalanche conditions. This is a good day to simply stay off of and out from under any steep open slope, particularly at middle and upper elevations.

Lawinenprobleme

  • Storm Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Very Likely
    Größe
    2–3

    “Stormy” pretty much sums it up. Wind slabs, storm slabs, and maybe even persistent slabs…No matter what you call it, very large and destructive natural avalanches could occur. This won’t be the day to try and tip-toe around avalanche terrain. Avoid places where avalanches start, run, and stop. 

    Even at lower elevations where the danger is slightly less, you could trigger avalanches big enough to bury you, and isolated slides could descend from above. 

    In some instances, avalanches could fail or step down into any number of deeper weaklayers that extend all the way back to mid-December. While we haven’t seen these types of slides at the Pass, they have occurred in other zones. These avalanches would be many feet deep and could wrap around terrain features.

    (12/20/2022)

    Example: Storm slabs of all sorts of shapes and sizes could occur Tuesday, including deep ones involving all the recent snow. 

    Photo: WSDOT Avalanche Team

Avalanche Discussion

A major winter storm crescendos Monday night and into Tuesday morning. With peak warming sometime around midnight, we could see a significant natural avalanche cycle during the overnight hours. By sunrise, temperatures should be cooling, which will help. However, continued heavy snowfall and very strong winds will maintain a higher likelihood of additional natural slides. 

Lower in the terrain, rain on the snow Monday night should help confine the danger to the new snow. Even still a few bigger slides may descend from above into lower-elevation runouts. 

If precipitation tapers later in the day, you could see the hazard slowly decline.

The upper snowpack has several layers (Jan 4, Jan 2, 12/25, and Solstice Crust) that contain crust/facet combinations. Some snowpack tests continue to show these layers fail and propagate, others do not. There’s enough evidence to suggest any one of these weaklayers could produce very large avalanches. 

On Monday, avalanche professionals reported very small natural and triggered slabs mainly in very steep and rocky terrain. Easterly flow kept the Pass cold all day long with light, fluffy snow.

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