Avalanche forecast

Snoqualmie Pass

Northwest Avalanche Center
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Avalanche danger

Thu
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
2 · Moderate
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Out of date — this forecast expired 3 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

Wednesday should be a transition day between weather patterns. Keep an eye on the snow surface and how it is changing to determine what type of avalanche problem you need to manage. If the snow is wet and sticky, the potential for wet slides is increasing and you should head for shadier slopes.

Avalanche problems

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–2

    With a bump in temperatures and fewer convective showers forecasted for Wednesday, it’s time to start talking about wet avalanche activity more formally than the past few days. You could run into issues if solar input is able to destabilize the recent cold dry snow sitting on the surface. If the snow is getting wet and sticky, shedding from trees and rocks, or there are new rollerballs on steep slopes, then Wet Loose avalanches could soon follow. These slides typically start at a point and fan out as they move downhill, sometimes growing large or triggering slabs in the process. Your best mitigation strategy will be to head for shaded slopes with limited overhead hazard.

    On slopes that continue to hold cold dry snow, you could trigger some Dry Loose avalanches that behave similarly to their wet counterparts. Don’t get swept off your feet in consequential terrain.

    (4/2/2023)

    Snow started to get heavier and fail easily after a brief period of sunshine on 4/2.  [Kendall Knob]

    Photo: Public Observation

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–2

    You may still be able to trigger lingering slab avalanches in wind-effected terrain. Focus your attention on specific terrain features such as steep unsupported slopes, convexities, confined chutes/gullies, or the lee side of ridgelines. These are the most likely locations to trigger one of these slides. Visual clues such as textured surfaces or recently formed cornices can help you identify aspects where these slabs may be lingering. In some locations, they could be hidden under a few inches of snow. If that’s the case, you’ll need to feel for differences in density under your feet to locate them.

    (4/2/2023)

    A widely breaking avalanche on a convex slope that was human-triggered on 4/2. The skier was caught, carried, and partially buried. [Great Scott Bowl]

    Photo: Public Observation

Avalanche Discussion

Wednesday should be the warmest and potentially sunniest day of the week as we transition between weather systems. That doesn’t mean you won’t still see a convective shower or two, but they should be few and far between. The trade-off is that you’re more likely to encounter avalanches due to solar input than in recent days. The timing will have to work out between chilly morning temps and increasing clouds in the afternoon. On some slopes, a surface crust may need to break down before the threshold for wet avalanches can be reached. 

We’re still focusing our attention on the storm snow sitting above the 3/31 interface. You should find this interface roughly 1-1.5 feet below the surface. Its crusty nature makes it a potential bed surface for avalanches to run on.

Over the weekend, avalanches were easy to trigger in the recent storm snow and we received numerous observations of human-triggered slides. Multiple reports indicated that individuals were caught and carried and in some cases partially buried. Most avalanches are thought to have failed on a subtle layer a few inches above the 3/31 crust. The odds of triggering similar slides have decreased but may not be fully eliminated.

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