Boletín de aludes

Snoqualmie Pass

Northwest Avalanche Center
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Peligro de aludes

Tue
Alta montaña
2 · Moderado
Límite del bosque
2 · Moderado
Bajo el límite
1 · Débil
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Desactualizado: este boletín caducó 6 years ago. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

Snow showers should continue to impact Snoqualmie Pass on Monday, increasing the amount of snow sitting on top of a crust. Take some time to get a feel for the upper layers of the snowpack as you travel. If you find that the snow is no longer light and fluffy, but rather stiffened by the wind or heavier and more cohesive, then head for terrain less than 35 degrees.

Problemas de aludes

  • Wind Slabs

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

    There is plenty of low-density snow sitting on top of the 12/9 crust available for the wind to transport, and we have reports of confirmed Wind Slabs from over the weekend. Keep these slabs on your radar on Monday where you will most likely find them on specific terrain features such as at the base of cliffs or on the sides of gullies. Look around and take note of any blowing snow, textured surfaces, or smooth pillow-like piles of snow to help you determine where Wind Slabs may have developed. If you notice clues of unstable snow such as shooting cracks or whumpfing collapses as you travel, steer around wind-loaded terrain.

    (12/12/2020) On Saturday, this human triggered Wind Slab on the north side of Chair Peak swept two travelers off their feet.

  • Loose Dry

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

    Low-density snow continues to fall on a stout rain crust and with the right conditions, Loose Dry avalanches could run on Monday. Often called sluffs, Loose Dry avalanches start at a point, then entrain additional snow and fan out as they move downhill. These slides can run quickly and far distances and are capable of sweeping you off your feet. So be aware of where you are in terrain and avoid stopping underneath steep slopes or near terrain traps. Unsupported slopes and terrain features steeper than 35 degrees have a higher likelihood of producing these avalanches.

    (12/12/2020) Dry Loose avalanches should remain on your radar on Monday on steep slopes if you find unconsolidated snow on top of the 12/9 crust.

Avalanche Discussion

Last week, warm temperatures followed by a rain event helped to create a stout crust (12/9) throughout the Snoqualmie zone. This thick crust is being considered our new ground for the time being and has accumulated close to a foot of snow on it in some locations. Other areas are seeing far less snow on the crust, but the dynamics remain the same. To this point, the snow on top of the crust has remained light and fluffy without much cohesion, except for in specific areas where the wind was able to drift the snow into stiffer slabs. This light and fluffy snow contains some weak snow crystals that we are watching as we continue to increase the load over the crust. This process should continue on Monday before a larger storm impacts the area heading into Tuesday. However, take note of how the snow feels on Monday. If you find that the snow is no longer powdery but is more cohesive, the possibility of avalanches is increasing and you may be dealing with a Storm Slab problem and you should default to slopes lower than 35 degrees. We expect any avalanche activity to be confined to the snow above the 12/9 crust. Don’t get caught off guard as we move through the different waves of storms this week, the hazard will be increasing at some point.

Recent weather wreaked havoc on the snow around Snoqualmie Pass, leaving us with variable and potentially difficult travel conditions. Firm surfaces abound under the recent fresh snow. The snowpack at lower elevations eroded during the warm and wet weather amplifying early season conditions. New snow will help, but you will likely encounter numerous open creeks, downed logs, and exposed obstacles. Some of these obstacles will now be shallowly buried, so be cautious and give yourself extra time to deal with these variable conditions.

During the ongoing Covid-19 pandemic, continue to follow the latest guidance from local, state, and federal health officials. Avoid unnecessary risks that could impact first responders and stress medical resources.  Wear a mask when appropriate, practice social distancing, and consider recreating closer to home.

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