Bulletin d’avalanche

Snoqualmie Pass

Northwest Avalanche Center
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Danger d’avalanche

Sun
Alpin
2 · Modéré
Limite forestière
2 · Modéré
Sous la limite
1 · Faible
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Périmé — ce bulletin a expiré 4 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

An incoming storm should increase avalanche hazard throughout the day on Saturday. Triggering a slide could be more likely during periods of heavy snow or wind. Be sure to steer around features where the wind is drifting the snow into deeper piles.

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    1–1.5

    The potential for triggering a Wind Slab should increase as the day progresses on Saturday. Wind ahead of the onset of precipitation could drift already in place dry snow into shallow slabs. As the snow starts to fall, look for these slabs to increase in thickness and become more reactive. You might find slabs on a variety of aspects due to an expected midday wind direction change. Regardless of aspect, these slabs will be more likely near ridgelines, convex slopes, or rocky features such as the base of cliffs and confined gullies. Using small test slopes can help give you an indication of how the new snow is reacting to your weight. Take a look for actively blowing snow, freshly built cornices, or new drifts to help you identify wind-loaded features to avoid. 

    (1/20/2023) A small skier triggered wind pocket on a convexity. Note the slightly textured surface. Photo: Andy Harrington

Avalanche Discussion

While the hazard level remains at Moderate for Saturday, the problem set and severity of that Moderate rating are different than what you may have experienced on Friday. We anticipate increasing avalanche hazard throughout the day as a storm works its way into the zone. It is expected to bring snow and strong winds, impacting the Pass through the evening into Sunday morning. If you happen to be out into the early evening hours, you might see conditions start to approach Considerable at upper elevations where more wind effect is expected.

The new snow should be falling on a variety of surfaces and further increasing the depth over the prominent MLK crust. On Friday, NWAC forecasters and multiple avalanche professionals noted a sun crust on many slopes that see direct sunshine and weaker surfaces on protected shady slopes. Those weak surfaces could persist and become buried by this storm or could get wiped out by the winds. If it’s preserved, you might see isolated avalanches breaking in some surprising ways such as spanning far distances or wrapping around terrain features. Make sure you take a minute to check the bonding of the new snow to the old surface to see if it is failing easily wherever you’re recreating.

There were also some natural loose avalanches and a couple of pockets of unstable Wind Slab noted by professionals on Friday. While the wet loose avalanches shouldn’t be an issue on Saturday, you could still find lingering Dry Loose avalanches on steep slopes that are protected from the sun and wind. Any avalanche should be confined to the snow above the MLK crust (about 1.5 feet below the surface) and the majority should revolve around the incoming storm snow.

Régions couvertes