Avalanche forecast

Snoqualmie Pass

Northwest Avalanche Center
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Avalanche danger

Wed
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
2 · Moderate
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Highlights

Snowfall should eventually replace rain at Snoqualmie Pass as temperatures drop on Tuesday. As a result, you could encounter some new snow problems as you ascend in elevation. However, the threat for larger and scarier wet avalanches will remain. Don’t linger under hanging blocks of snow or slopes containing large cracks. 

Avalanche problems

  • Glide Cracks

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2–2.5

    It is going to take a bit of time for the snowpack to adjust to the amount of rain it just ingested. As a result, wet avalanche activity may diminish but will not be fully eliminated on Tuesday. As the storm cools and liquid precipitation tapers, the focus now shifts toward the unpredictable and dangerous Glide avalanches. These avalanches fail without warning and aren’t a problem you can easily manage. Steer clear of steep slopes where you see crevasse-like cracks or hanging blocks of snow on rocky ledges. 

    Although we’re changing our focus toward Glides, other wet avalanches such as Wet Loose, Wet Slab, and Cornice collapses are all still on the table Tuesday. The travel advice for these problems is largely the same - stay clear of open slopes over 35 degrees wherever you encounter a wet and punchy snow surface. Any triggered wet avalanche has the potential to entrain significant snow and grow large. 

    (12/26/2022)

    Example: A glide avalanche plus a separate Glide crack where the snow has not yet released. These occurred as temperatures cooled a few days after a rain-on-snow event earlier this season.

    Photo: Alpental Pro Patrol

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1

    As temperatures drop and snowfall returns to the Pass, you could encounter some new snow problems. We anticipate any accumulation to have a favorable bond to the warm and wet surface. That said, be leery of features where the wind formed slightly deeper and firmer slabs. Textured surfaces, sharp cornices, or actively blowing snow can help you locate these wind-loaded pockets. Pay close attention near ridgelines or rocky terrain where you’re more likely to trigger one of these small avalanches.

    (3/25/2023)

    Example: Look for Wind Slabs on specific terrain features such as in confined chutes like this one.  {Kendall Adventure Zone N 5300']

    Photo: Public Observation

Avalanche Discussion

As of Monday evening, the Pass has picked up close to 2 inches of water since Saturday afternoon. Most of this precipitation fell with high freezing levels meaning it rained to the tops of the peaks for the first time in a few months. 

Rainfall should continue into Monday night as freezing levels slowly lower and snow returns. If everything goes as planned, we should see snow replace liquid precipitation down to road level on Tuesday. Unfortunately, it’s springtime and the weather doesn’t always go as planned, so don’t be surprised if you encounter wet precipitation - whether that be rain, snow, or some combination (snain). There’s a chance you could even see a few sun breaks in the afternoon.

Observations from this wet and warm period are essentially non-existent, so a great deal of uncertainty surrounds conditions in the mountains and the extent of recent avalanche activity. Reports from the neighboring West South and Steven’s Pass zones relay that large wet avalanches occurred on Monday.

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