Bollettino valanghe

Snoqualmie Pass

Northwest Avalanche Center
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Pericolo valanghe

Mon
Alta quota
3 · Marcato
Limite del bosco
3 · Marcato
Sotto il limite
2 · Moderato
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In sintesi

Even as the storm wraps up and skies start to break Sunday, dangerous avalanche conditions should remain. You could trigger slides in a variety of locations like wind-loaded slopes, sunny aspects, or rocky complex terrain. Give the snowpack time to heal by staying off open areas greater than 35 degrees.

Problemi valanghivi

  • Loose Wet

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

    There’s plenty of loose snow out there. The question is the sun. Intense graupel snow showers could alternate with periods of sunshine. If these sun breaks linger, expect snow to fall off rocks/trees/cliffs and produce natural loose avalanches. Call them wet, call them dry, the result is the same... avalanches. Don’t spend too much time under steep sunny slopes. Most of these slides should remain small, but in bigger terrain, they could entrain enough snow to take you for a nasty ride.

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    1–2

    Another strong E-S wind event built a fresh batch of slabs at the tail end of this storm. Some of these wind-loaded pockets triggered easily on Saturday. You could find wind slabs in some unusual locations and even hiding under an inch or two of softer snow. Keep your eyes peeled for clues of where these slabs might lurk. Drifts, cornices, and the snow blown out of the trees may give you the best hints as to where to look and what aspects to avoid. 

    Common places to encounter winds slabs include below sharp cornices, along the base of cliffs, in the tops of chutes, and on the sides of mid-slope gullies. With the ferocity of the winds, you may even bump into a wind-loaded pocket in the upper end of the below treeline band. With the information we have from Saturday, assume wind slabs exist in most mid and upper elevation terrain until you can confidently rule them out.

    (3/4/2023)

    Wind slab near Gold Creek/Rampart Ridge on Saturday 3/4.

    Public Field Report: Rampart Ridge

    Photo: Griffin M

Avalanche Discussion

Sunday will be a post-storm transition day. This can lead to tricky conditions as the snowpack continues to adjust to the recent load and the skies start to break. This can be particularly challenging when there is so much fun soft snow on the ground. 

This storm has brought around 2 feet of light fluffy snow to the Pass since Thursday. All this powder fell on top of another 2 feet of snow from last weekend. Not surprisingly, travelers continually report deep conditions! Strong E-S wind on Saturday (3/4) redistributed the new snow at mid and upper elevations. Last week, a post-storm wind event similar to this one resulted in numerous unintentional human-triggered avalanches including at least two individuals being caught and carried. 

Avalanche activity during this storm has been generally limited to natural and triggered loose dry avalanches on very steep slopes at all elevations and a few shallow wind slabs. However, one small intentionally triggered wind slab stepped down to an older snow layer (2/25) Friday. This resulted in a large (D2) avalanche, 2.5 ft (80cm) deep, that ran 300 vertical ft downslope (N, 4300ft). This older interface has been on our radar, but until this event, we had not seen any activity occurring at this interface. While avalanches failing into the older snow should be rather isolated, they could happen. It would be most likely in shaded sheltered terrain, where weak snow grains (surface hoar/facets) may have survived. Consider the consequences of these potentially larger avalanches before stepping into larger, open, and connected slopes. 

Regioni coperte