Avalanche forecast

Snoqualmie Pass

Northwest Avalanche Center
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Avalanche danger

Fri
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
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Out of date — this forecast expired 4 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

Be leery of wind-loaded pockets at upper elevations. Look for shooting cracks or firm wind-pressed snow to help you identify these areas to steer around. In other areas, generally safe avalanche conditions will persist.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–1.5

    At upper elevations, you could find some isolated pockets of hard Wind Slab. These were identified by multiple professionals on Wednesday but were stubborn to trigger.  That said, hard slabs are notoriously difficult to assess and can break above you or in surprising ways, so be leery. In some locations, these slabs were hidden under the recent new snow, making them more difficult to find. Wind textured surfaces or smooth pillow-like piles of snow can be used as visual clues to help clue you into wind-loaded terrain on the surface. Feel for stiff (but not firm and icy) snow that might feel hollow to further help identify Wind Slabs. Any potential avalanche should be relatively small, but don’t get surprised by one in consequential terrain. Features such as steep unsupported slopes or convexities near terrain traps come to mind as areas that could have more serious consequences. 

    While you could find a Wind Slab on any aspect, we are specifically concerned about ones on shady slopes, which is represented in the distribution rose. This is because slopes that do not see direct sunshine may contain thicker slabs that potentially overlay weak (faceted) snow. If this setup exists, avalanches have the potential to break in surprising ways and span the width of terrain features.

    (3/9/2022)

    Stubborn hand shear result @ 5450' on N aspect of Chair Peak. Areas of hard Wind Slab were reported on multiple northerly slopes at Snoqualmie Pass on 3/9. In many areas, weak snow was found beneath.

    Photo: Public Observation

Avalanche Discussion

On Wednesday, NWAC forecasters in the Alpental Valley found around 3-4” of low-density new snow overlaying the firm surface created by last week’s atmospheric river. The caveat to this was on high elevation slopes that do not see direct sunshine, where up to 10” of snow was found over the firm crust. This number could vary depending on wind deposition, and includes the snow that fell in the middle of last week. On more sunny slopes, last week’s snow has gone through a melt-freeze cycle and molded into the atmospheric river crust before being buried. That process did not happen on the shady slopes, where instead the snow lost strength (faceted) over this past weekend. NWAC forecasters, multiple avalanche professionals, and recreationalists all reported finding hard Wind Slabs overlaying faceted snow on northerly facing slopes. This isolated but potentially dangerous setup is what's driving our Moderate hazard rating.

In other areas, minimal new snow combined with the absence of hard slabs and faceted snow should allow for generally safe avalanche conditions. You will mostly be dealing with small Dry Loose avalanches (sluffs) that are capable of running far and fast on underlying firm surfaces. 

You could find that one of the bigger challenges is dealing with difficult travel conditions. A few inches of fresh snow certainly helped, but wasn’t enough to cover up the widespread avalanche debris, open creeks, rain runnels, or other variable surfaces the atmospheric river left behind. Allow yourself extra time to navigate these challenges and bring the right equipment if you are traveling on firm slopes to prevent a long and uncontrolled fall.

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