Boletín de aludes

Snoqualmie Pass

Northwest Avalanche Center
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Peligro de aludes

Mon
Alta montaña
2 · Moderado
Límite del bosque
2 · Moderado
Bajo el límite
2 · Moderado
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Desactualizado: este boletín caducó 4 years ago. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

Easter Sunday may be a bit of a transitional day between storm systems. As the weather changes, so could the avalanche problem from dry to wet. If the return of the sun and some elevated temperatures are producing signs of wet avalanches such as rollerballs or snow shedding from trees and rocks, hop over to shadier slopes.

Problemas de aludes

  • Loose Wet

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Possible
    Tamaño
    1–1.5

    Sunday should be the warmest day we’ve had in the last two weeks and sunshine could combine with the warmer temperatures to weaken the snow surface. If it's sunny out and you notice that the snow is starting to get wet and sticky or see it shedding from trees and rocks, then it's time to start thinking about Wet Loose avalanches. If they occur, these slides will be more likely on steep slopes that see direct sunshine. This is April, however, so there’s a chance you could see them on more northerly aspects in some locations or they could linger after the sun has disappeared behind the clouds. Wet Loose avalanches often start at a point before fanning out and entraining snow as they descend downhill. Precursors such as rollerballs and pinwheels can let you know that the snowpack is reaching the threshold for producing these slides and you should head for shadier slopes.

    (4/16/2022)

    Recent Wet avalanche activity from 4/15. Rollerballs, pinwheels, and snow shedding from trees and rocks are all signs that the snow is reaching the threshold for wet avalanches.

    Photo: Andy Harrington

  • Wind Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Possible
    Tamaño
    1–1.5

    Before the snow has the opportunity to heat up, you could encounter some freshly built Wind Slabs at higher elevations or in extreme terrain. We are expecting some new snow on Saturday night accompanied by moderate winds, which could be just enough to produce some unstable pockets near ridgelines or confined rocky chutes. If you notice fresh pillow-like drifts, textured surfaces, or inconsistent snow depths as you travel, be on the lookout for nearby wind-loaded terrain to avoid.

    (4/13/2022)

    Textured snow surfaces show that the wind has been drifting the snow, possibly into nearby Wind Slabs.

    Photo: Craig Muderlak

Avalanche Discussion

Sunday should be a bit of a lull between stormy weather patterns at Snoqualmie Pass. A short-lived window of nicer weather should deliver sunshine and warmer temperatures than we have seen in recent weeks, at least for part of the day. There’s a chance we wring out a few inches of snow on Saturday night before this transition occurs. Increasing clouds ahead of the next storm system should reach the zone sometime in the early afternoon hours. 

These transitional days can be difficult to forecast and nuance, especially during springtime weather, but your best course of action is to watch how the weather is changing the snow surface throughout the day. If there is cold dry snow in your location, you should be dealing with primarily dry avalanches such as Wind Slabs or Dry Loose. If it’s sunny and warm or the snow surface is wet and sticky, you could be in wet avalanche territory. Watch out for Wet Loose or springtime shedding avalanches such as cornice failures or snow falling from rocky ledges. The size and frequency of these avalanches could depend on the duration of warmer temperatures or sunshine. Variability in the weather means conditions could vary between drainages or from aspect to aspect.

The current snowpack around the pass has become a bit aspect-dependent, with previous solar input driving the variability. On slopes that have seen direct sunshine lately, a surface crust of varying thickness exists and recent rollerballing and tree bombs have littered many areas. Below the surface crust, cold dry snow still exists above the 4/8 interface. Shadier slopes lack this crust and instead you will find generally right-side-up dry and settled storm snow. Regardless of aspect, we have found 2-2.5 feet of snow exists over the 4/8 crust in most locations and do not anticipate any avalanches deeper in the snowpack at this time.

We have extended our forecasting due to the stormy weather to help you out. That means we still need you to share information with us by submitting public observations about what you're seeing out there. Help us build a better product for you.

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