Bollettino valanghe

Snoqualmie Pass

Northwest Avalanche Center
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Pericolo valanghe

Mon
Alta quota
4 · Forte
Limite del bosco
4 · Forte
Sotto il limite
3 · Marcato
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In sintesi

Very dangerous conditions are expected to develop on Sunday as an atmospheric river takes aim at Snoqualmie Pass. Wet avalanches large enough to bury and kill you will occur on most steep slopes. Sunday is not the day to hang out in the mountains, especially in avalanche terrain.

Problemi valanghivi

  • Loose Wet

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

    Wet avalanches will be prevalent throughout the mountains on Sunday, including slabs, loose, glide, and cornice collapses. You will likely see snow falling off rocks and ledges that are harder to put a name to. We’ll just call them "spring shedding-type" slides. The problems could vary from slope to slope or at different points during this rain event, sometimes overlapping. Any avalanche has the potential to grow large as it gouges down into older layers or entrains snow as it descends. Some could run far distances down into the trees. Sunday will not be a good day to hang out in terrain where avalanches can start, run, or stop.

    Although some drier snow may fall at upper elevations to start this event, rising freezing levels mean that any new snow problems will eventually transition to wet snow problems. Don’t overthink it, Sunday is not the day to play in the mountains.

    (1/15/2023)

    Example: Wet avalanche debris from an atmospheric river event earlier this season. These loose and slab avalanches ran low in the valley. 

    Photo: Dallas Glass

Avalanche Discussion

As far as atmospheric rivers go, the one set to hit Snoqualmie Pass on Sunday could be considered modest. That said, we’ve seen what even modest rain events can do to our snowpack and now we have the added dimension of springtime to throw into the mix. 

Although the snow surface may already be wet from recent rain and sunny springtime weather, the moist snow only extends so deep. Below the wetting front, a layered cold dry snowpack exists with multiple interfaces capable of failing if water is able to percolate to their depth. And there are plenty of precariously hanging cornices or blocks of snow on rocky ledges that need to come down as we transition from winter to spring.

With a poor overnight refreeze expected, rising snow levels, and increasing precipitation rates, you could say that the hazard will escalate throughout the day. Or you could just keep it simple and realize that Sunday will be a lousy day to spend in the mountains and very dangerous avalanche conditions are expected. So you may as well stay home until this storm has wrapped up in a few days.

Regioni coperte