Lawinenlagebericht

Snoqualmie Pass

Northwest Avalanche Center
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Lawinengefahr

Mon
Hochgebirge
2 · Mässig
Waldgrenze
2 · Mässig
Unterhalb
2 · Mässig
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Kernpunkte

Recent human-triggered avalanches are an indication that the snowpack hasn’t fully settled post-storm. You could find that wind-loaded features such as confined gullies or convex slopes are the most likely location for you to trigger a slab of your own on Sunday. Keep an eye on the sky and if the snow is changing throughout the day as a result of solar input. 

Lawinenprobleme

  • Wind Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1–1.5

    The most likely location for you to trigger a slab avalanche should be in wind-loaded terrain on Sunday. Look for features that look “fat” with pillow-like drifts compared to the surrounding area near ridgelines, confined gullies, or on convex rollovers. You may see other visual clues such as textured surfaces or sharp cornices in the nearby terrain that can help key you into which way the wind was blowing and thus wind-loaded aspects. Using small test slopes or performing uptrack tests in benign terrain can help you identify how the recent storm snow is reacting to your weight as a traveler. If you notice cracking or blocks of snow failing easily during your tests, choose an alternate path avoiding wind-loaded slopes.

    (3/25/2023)

    This human-triggered slab occurred just off a ridgeline and failed near the base of the new storm snow. [Roaring Ridge, West Bowl. N 4800]

    Photo: Bryan Eastes

  • Loose Wet

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1–1.5

    Sunshine and temperatures are forecasted to slowly increase on Sunday which could be enough to kick off some Wet Loose avalanche activity. That said, temperatures aren’t skyrocketing and we’re not expecting full sun, so this problem may not materialize. You’ll need to keep an eye on the weather and how the snow surface is changing throughout the day. If the snow is getting wet and sticky or the sun is out for a prolonged period of time, make a judgment call on if you should head for shadier slopes to avoid this hazard. If you see new rollerballs or fan-shaped avalanche debris due to solar input, then the decision is likely made for you. You’ll know it’s time to head for sun-protected slopes keeping aware of hanging blocks of snow such as cornices or glide cracks above you.

    (3/18/2023)

    Wet Loose avalanches on Kendall Peak occurred due to solar input on 3/18. Most originated near rocky terrain.

    Photo: Rachel Gronvold

Avalanche Discussion

We’re coming out of a multi-day storm that dropped roughly 8-18 inches of snow around Snoqualmie Pass. On Sunday, you may see a few showers pass through here and there, but the precipitation is largely finished. You’ll need to manage lingering storm instabilities confined to the new snow during your travels and keep an eye out for changing conditions due to solar input as noted above.

On Saturday, recreationalists, avalanche professionals, and Alpental Pro Patrol all reported small slabs triggered at both the base and within the recent storm snow (3/22 interface). Most of these avalanches appeared to be on steep convex slopes or near rocky terrain such as gullies or the base of rocks and all of them were soft. One avalanche professional traveling at upper elevations reported some whumpfing collapses on a west aspect. Upon investigation, he received sudden collapses on weak snow 1-2 inches above the sun crust. Sun breaks allowed the snow at lower elevations to get moist throughout the day and a few small rollerballs were reported. NWAC forecasters noted that much of the storm snow comprised of rimed precipitation particles/graupel at mid-elevations.

Prior to the storm, mostly warm and sunny weather impacted the zone for the majority of the past week. A surface crust formed on most aspects and elevations. The caveat is high-elevation northerly terrain (above ~4500’) where dry soft snow survived and possibly faceted (weakened) during this spell. As alluded to above, there could be some weak snow on other aspects as well. Be sure to check the bond to the old snow surface (3/22 interface) throughout your travels. All avalanche activity is expected to occur at or above this interface on Sunday.

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