Bollettino valanghe

Snoqualmie Pass

Northwest Avalanche Center
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Pericolo valanghe

Wed
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
2 · Moderato
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Non aggiornato — questo bollettino è scaduto 3 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

If you’re going to trigger a larger avalanche it will probably be in wind-loaded terrain. Unfortunately shifting winds and a few inches of fluffy snow could make spotting these pillow-like slabs tricky. Steer around any steep slope where you suspect the wind formed slightly deeper slabs.

Problemi valanghivi

  • Wind Slabs

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

    It may take a bit more investigation than normal to identify and avoid wind-loaded features. Some of the common clues we often use may not be visible or could be misleading. Assume wind slabs exist on all exposed features until you can prove otherwise. This includes wind-affected ridges, the base of cliffs, and rock walled chutes. 

    Through the course of this storm, winds have switched from west, to east, to south, and back to west. Not surprisingly, this may have built wind slabs in lots of places, including areas you may not be used to. With the potential for odd loading patterns, use terrain to your advantage by seeking out lower consequence slopes.

    Some of these slabs may be fresh and fail easily. Others could be older, harder to trigger, but deeper. If you feel firm or hollow snow, seek out less wind-affected or lower angled terrain. 

    (1/8/2023)

    Example: You could find wind slabs in terrain like this Tuesday. 

    Photo: Public Observation

  • Loose Dry

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

    Outside of wind-affected areas, reports have been of very light fluffy snow that’s poorly bonded to the old surface. This could result in loose dry or very soft slab avalanches in steep terrain. Some of these slides could run quickly or travel far on a firm bed surface. While avalanches like this can be relatively easy to manage, don’t let them catch you off guard if your traveling in cliffy areas or above an open creek.

    If the sun pokes through in the afternoon, you may see snow shed from rocks and cliffs resulting in a round of natural loose slides. 

Avalanche Discussion

As of Monday afternoon, the Pass had picked up more than a foot of snow since Saturday night. This fell with cold temperatures resulting in very low-density snow and, the good news is more could fall Monday night into Tuesday. 

Prior to the storm, a wide variety of snow surfaces were reported including icy crusts, wind-textured snow, soft powder, sugary facets, and feathery surface hoar. Now all these old surfaces are buried. You may find that the snow responds differently from one slope to the next. Generally, backcountry travelers reported poor bonding between the old and new snow, especially at lower elevations where an icy crust was more prevalent. 

Easterly winds on Monday easily transported the new snow. One avalanche professional in the Gold Creek area reported blowing snow, drifting, and firmer wind slabs in the near treeline band. 

At the moment we expect any avalanche activity to remain at or above the new/old interface (2/25). While you can still identify older interfaces like 2/17 and 2/13, we haven’t seen any recent slides on these older layers.

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