Lawinenlagebericht

Snoqualmie Pass

Northwest Avalanche Center
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Lawinengefahr

Tue
Hochgebirge
2 · Mässig
Waldgrenze
2 · Mässig
Unterhalb
2 · Mässig
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Veraltet — dieser Lagebericht ist 5 years ago abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

A return to full sunshine and rising freezing levels may reinvigorate a Glide avalanche cycle that occurred over the weekend. Take note of how the snowpack is changing throughout the day and be diligent with your route selection. You should put plenty of space between yourself and overhead hazards.

Lawinenprobleme

  • Glide Cracks

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    2

    Sunshine and warm temperatures on Monday will maintain our concern for Glide avalanches at Snoqualmie Pass. Glide avalanches are erratic and very difficult to predict but often occur during periods of warm temperatures, prolonged sunshine, or rain. These avalanches shed large amounts of snow off smooth rock faces onto the slopes below, often triggering other types of avalanches. Over the weekend, multiple Glide avalanches up to size D3 were observed in the Alpental Valley due to a combination of sunshine and warm temperatures. This red flag tells us that these slopes are ready to fail, demanding that you are aware of your overhead hazard at all times. Although Glides are unpredictable, you can minimize your hazard by choosing safe travel routes far away from slopes that contain large cracks in them.

    (4/4/2021) Multiple Glide avalanches as large as D3 descended on Saturday in the Alpental Valley. The largest slide on the right crossed a very popular travel route

  • Loose Wet

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1–2

    It may take a few hours, but snow surfaces should soften in the nice April weather, presenting an opportunity for Wet Loose avalanches to develop. These slides often start at a point, can entrain significant snow, and then fan out as they descend. On Monday, they could be confined to the recent storm snow or gauge down into older moist snow in the upper snowpack. If the snow surface has gotten sticky and wet or you are sinking into moist snow past your ankle, you should suspect Wet Loose avalanches. If you notice rollerballs and pinwheels or that there are fresh avalanches with fan-shaped debris piles, head toward shadier slopes and stay aware of your overhead hazard.

    (4/4/2021) Take the time to step off your mode of travel and see how deeply you are sinking into the moist snow. If you're sinking in deeper than your ankle, you should start to suspect wet avalanches. [Boot Pen: 40cm N ~4600']

Avalanche Discussion

On Sunday, NWAC forecasters made a trip up the Alpental Valley after reports of an active Glide cycle on Saturday. We found over 10 recent Glide avalanches up to size D3 and multiple smaller shedding-related avalanches. During our time in the field, we also witnessed two new shedding events, which had Glide’ish properties to them. Some of the slides over the weekend reportedly started when chunks of ice fell off cornices or cliffs, while others were true Glide avalanches. Regardless of how you want to characterize them, the bottom line is that it is springtime and the snow appears ready to shed. The snowpack goes through this transition period every spring with freeze-thaw cycles, cornice collapses, and rocks warming up and shedding their snow. This transition has begun but certainly has not been completed at Snoqualmie Pass. A layered and cold dry snowpack was still found on northerly aspects by NWAC forecasters on Sunday. A quick look around the pass by even the untrained eye will spot plenty of glide cracks and blocks of snow that are yet to fall. Continue to give cornices a wide berth by limiting your exposure traveling under them or on top of them. Much like glides, they are unpredictable but often fail during periods of nice spring weather or rain. And be sure to make your own observations, taking note of how the dynamic springtime weather is affecting the snowpack in your location. If you find that the snow is ripening up, springtime-related avalanches may follow.

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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