Boletín de aludes

Snoqualmie Pass

Northwest Avalanche Center
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Peligro de aludes

Sat
Alta montaña
2 · Moderado
Límite del bosque
1 · Débil
Bajo el límite
1 · Débil
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Desactualizado: este boletín caducó 3 years ago. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

A convergence zone is expected to enhance snowfall amounts at Snoqualmie Pass on Thursday night. The wind could drift this snow around into shallow slabs at upper elevations. Lower in the terrain, you may see some wind effect or loose snow running on a crust, but not a lot of avalanche danger. 

Problemas de aludes

  • Wind Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Possible
    Tamaño
    1

    There might be just enough snow and wind for shallow wind slab development at upper elevations on Friday. Look for actively blowing snow, new drifts, or textured surfaces to help indicate wind-loaded features to avoid. They will be more likely near the base of cliffs, on leeward ridgelines, or in rocky chutes. Although you may find wind effect lower in the terrain,  we don't anticipate slabs to be large enough to reach the threshold for consequential avalanches. 

    (2/4/2024)

    Small blocks of wind slab failing during an uptrack test.

    Photo: Julian Childs-Walker

Avalanche Discussion

On Thursday, NWAC forecasters took the sleds out on the Eastern half of the zone and found 3-4 inches of soft snow over the Early February Crust (EFC) at upper elevations. A thin melt-freeze crust formed on 2/7 on sun-exposed slopes, capping the soft snow above the EFC and creating a crust sandwich. No obvious instability was observed, and the EFC was stout and supported boots and snowmobiles.  The weather varied greatly throughout our relatively small zone. The eastern portion was partly sunny with flurries while grey skies and light snow showers graced the Pass proper. The western side of the zone was straight rain/drizzle. 

Observations from the Pass proper painted a different picture of the upper snowpack in recent days. Moist surface snow slid easily on the EFC under the weight of skiers or failed naturally during periods of sunshine in the Alpental Valley and Commonwealth Basin. Regardless of location, focus on the snow above the EFC when performing your stability assessments. On Friday, you could encounter loose (moist or dry) snow running on the Early February Crust on steep unsupported slopes. We do not have any concerns lower in the snowpack at this time. 

Although the snowpack was a little drier on the east side of the zone, the concern for travel hazards remained. Open holes and creeks, firm crusts, exposed natural hazards such as rocks and logs, and refrozen avalanche debris now litter the landscape. As each small storm wave rolls through, travel has been slowly improving throughout the week, but we have a ways to go. Give yourself extra time to avoid these hazards, and be prepared with flexible travel plans if your route is obscured. 

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