Bollettino valanghe

Snoqualmie Pass

Northwest Avalanche Center
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Pericolo valanghe

Sat
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
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In sintesi

Friday looks mostly sunny with slightly warmer temperatures than the Pass has seen all week. This could cause natural loose avalanches on steep slopes receiving direct sunshine. Don’t let one of these easy to predict and avoid slides push you over a cliff or into a deep gully.

Problemi valanghivi

  • Loose Wet

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–1.5

    With the sun expected to come out in earnest and temperatures to be the warmest we’ve seen all week, it's easy to think loose wet avalanche will be a concern on Friday. Although, this likely won’t be a large widespread avalanche cycle. Many slopes saw the sun at least once already this week and formed a thin breakable crust. This should help delay and limit the natural loose wet avalanche activity. However, below the crust cold dry snow remains. Expect to see plenty of new rollerballs and several loose avalanches. While we don’t expect these slides to grow very big, they could still pose a danger if they push you over rocks or into a creek. Pay attention to the terrain above you and don’t linger on or below steep sunny slopes when you start to find wet sticky snow at the surface. While you may see loose avalanches at any elevation, they will likely be more prevalent near treeline where the perfect balance of ample recent snow and less wind effect exists.

    (2/24/2022)

    Piles of rollerballs and two small natural loose avalanches originating on a steep sunny slope. 

    Photo: Robin Pendry

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–1.5

    You don’t have to look far to find evidence of wind transported snow at the Pass. Textured surfaces, scoured slopes, and sharp drifts abound. However, easterly winds that were responsible for most of the recent wind loading, often produce irregular and unusual wind slab patterns. That means you won’t find them on every feature, but they are out there. In fact, several human-triggered wind slabs were reported on Tuesday. You’ll need to look slope by slope to see if the terrain in front of you may hold a possible avalanche. If you find firm pillow-like drifts, consider seeking out lower angled or less wind-loaded routes. Now that these slabs are several days old, they may start to become harder to trigger.

    (2/23/2022)

    A skier triggered wind slab avalanche in the N Lundin Couloir on Tuesday. 15 x 15' wide and 8-12" deep. One skier was carried by the slide down hill, but was not buried and uninjured. 

    Photo: Public Ob

Avalanche Discussion

It’s been a very cold week at the Pass. This frigid weather has helped preserve much of last weekend’s storm snow. However, over the course of the week, the snow surface has started to change and become rather aspect and elevation dependent. As you ascend upwards, expect wind-affected surfaces to become more abundant, with some areas becoming quite variable and wind-sculpted. Outside of the wind effect, slopes that received direct sunshine formed a thin breakable surface crust capping the recent snow. In shaded terrain, this crust does not exist, and plenty of soft unconsolidated powder remains. 

Last weekend brought 16-20” of snow to the Pass at mid and upper elevations, with considerably less snow lower in the terrain. This snow buried a thin crust (2/19) which you may find 1-2” above the very prominent Valentine’s Day layer. While we don’t expect avalanches on these crusts or the weak snow around them at this time, we are watching them going forward.

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