Bulletin d’avalanche

Snoqualmie Pass

Northwest Avalanche Center
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Danger d’avalanche

Wed
Alpin
3 · Marqué
Limite forestière
3 · Marqué
Sous la limite
2 · Modéré
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Périmé — ce bulletin a expiré 3 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

Tuesday will be a relative lull between two powerful storms, but don’t let your guard down. Dangerous avalanche conditions exist and may be more difficult than usual to assess. Evaluate individual slopes carefully, and don’t expect them to all behave similarly.

Problèmes avalancheux

  • Storm Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    1–2

    New snow was measured in feet on Monday, meaning you could encounter multiple new snow problems on Tuesday. Our usual tips to gauge reactivity, such as using uptrack tests or small test slopes, may not work well when the snow is deep. The best option will be to dig down to the 2/24 interface with your hand or shovel, looking for heavy snow over weaker snow or easy and clean failures. Potential slabs will be larger as you ascend in elevation or in wind-loaded terrain. You could trigger loose avalanches on steep slopes in areas with unconsolidated snow. Evaluate each slope carefully and default to avoiding terrain over 35 degrees.

    (2/26/2024)

    A small natural slab avalanche on a steep unsupported slope. 

    Photo: Dallas Glass

Avalanche Discussion

The Pass picked up anywhere from 8 inches at lower elevations to over 2 feet of new snow at upper elevations during this last storm. On Monday, NWAC forecasters found that the storm snow was generally right-side up with a variable bond to the underlying surface (2/24 interface). In some areas, the snow was glued in due to warm temperatures, while others showed a weaker bond during tilt tests and hand pits. A few small natural and human-triggered avalanches were reported. 

The variable bond at the 2/24 interface isn’t all that surprising. Before the storm delivered a spread of precipitation types, an assortment of surfaces existed. Facets, surface hoar, firm crusts, and wind slabs had spotty distribution, leading to an unpredictable 2/24 interface from slope to slope.

The unpredictability continues deeper in the snowpack. Since our last atmospheric river, a series of small storms, clear weather, and strong wind events have created irregular potential weak layers above the stout Early February Crust (EFC). While we don’t suspect any of these layers will come into play on Tuesday, it’s not out of the question - particularly on high-elevation northerly terrain, where the snowpack is reportedly weaker. 

Régions couvertes