Bollettino valanghe

Snoqualmie Pass

Northwest Avalanche Center
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Pericolo valanghe

Sun
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
2 · Moderato
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Non aggiornato — questo bollettino è scaduto 4 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

While snow totals might not look super impressive, windy conditions likely built new reactive slabs on the lee sides of ridges and exposed features. Look for blowing snow, fresh cornices, and sharp drifts to point toward potentially wind-loaded terrain. Steer around these steep slopes if you see bright white pillow-like drifts.

Problemi valanghivi

  • Wind Slabs

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

    The main story with this storm revolves around the winds. So, it shouldn’t be much of a surprise when you find pockets of wind-drifted snow below cornices, in the tops of chutes, or along the base of cliffs. What could make this round of wind slabs unique is how easily they trigger. This is always very hard to forecast, but some of these new slabs will rest on firm slick crusts or maybe even weak sugar facets. So, while they should be relatively shallow, these slides could fail easily and run quickly. Use visual clues like blowing snow, cornices, and drifts to help anticipate wind-loaded slopes. Although we don’t expect these slabs to grow very large, they could be plenty big enough to take you for a ride or flush you down a couloir.

    (1/24/2023) Visual clues of possibly wind loaded slopes. Photo: Dallas Glass

  • Loose Wet

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

    At lower elevations, there are several factors that could contribute to small loose wet avalanches. Warming temperatures, green housing with thin clouds, rain, or even periods of sunshine could all cause the few inches of new snow to roll downhill. In general, we expect this to be primarily a rollerball event, but you could see a few small loose wet slides. Some of these avalanches may even travel far down slope over a firm crust. If you start encountering wet sticky snow, notice small point release slides, or see snow shedding from trees, think loose wet avalanches. Don’t let one of these small slides carry you into a creek or over a cliff.

    (1/14/2023)

    You may see rollerballs like this if the new snow warms up due to any number of factors. 

    Photo: Public Observation

Avalanche Discussion

It’s always a bit of a rude awakening when we transition out of a relatively quiet weather period into a more active pattern. The snowpack can change quickly and often there is a higher level of uncertainty about how these avalanche problems and danger will develop. Prior to this storm avalanche professionals and public observations reported a wide variety of snow surfaces around the Pass. This included very firm crusts, sugary facets, feathery surface hoar, and old wind textured snow. As storm totals start to increase, you may find the snow reacts differently from one slope to the next. Fortunately, we expect the avalanche activity to occur at or above the latest (2/3) interface. This should allow you to use lots of quick, moving observations like hand pits, small slopes, and uptrack tests to see if the snow fails or cracks easily. 

Even though the 2/3 interface is our primary layer of concern, you can still find other lingering layers in the upper snowpack. Typically you’ll see ~2ft of snow over the very prominent MLK crust. At the moment we don’t expect any avalanches on these older layers/crusts.

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