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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Non aggiornato — questo bollettino è scaduto 4 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Even though the snow totals from this storm don’t appear very impressive, the wind could form a new round of slabs along the lee sides of ridges and near the base of cliffs. Look for clues like drifts and sharp cornices to help you anticipate potentially wind-loaded slopes you may want to avoid.

Problemi valanghivi

  • Wind Slabs

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

    This is the winter of wind slabs at Snoqualmie Pass. And, Friday you may have a fresh batch to contend with as you travel. What could make this round unique, is an inch or two of soft snow helping to hide them from your view. Look for drifts behind trees and rocks to figure out local wind patterns and anticipate potentially wind-loaded slopes. Since it will be harder to spot the edges of the slabs, give them plenty of space by using lower angled or less wind-affected terrain. 

    Fortunately, most of these potential avalanches should stay relatively small. However, some of them could grow large enough to take you for a nasty ride or flush you down a chute.

    (2/9/2023)

    A small wind slab in a classic location, below a cornice on a steep rocky slope. 

    Photo: Andy Harrington

  • Loose Wet

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

    This problem is a little tricky and it may not happen, but we’ve reached that time of year when sunshine following a storm typically results in natural loose wet slides. So, if the sun comes out, start thinking about this issue. Snow shedding out of trees, new rollerballs, and small point-release slides all indicate the snow surface is becoming wet and unstable. Pay attention to the terrain above you and don’t let one of these small slides catch you by surprise. 

    This problem will likely be the most dangerous in the near treeline band where enough soft snow exists to produce legitimate avalanches. At lower elevations, minimal new snow should help limit the size and hazard of these avalanches.

    (2/1/2023)

    Example of a loose wet from steep sunny terrain earlier this month. 

    Photo: Andy Harrington

Avalanche Discussion

Overnight winds and snow totals should give you a pretty good idea of how this forecast is tracking before you even get on the snow. Because the wind slabs will be fresh in the morning, expect them to be the most reactive right out of the gate. As the day progresses, they could become harder to trigger. Any wind slab decrease in danger could be offset by a rise in wet avalanche issues. 

Avalanche professionals around the Pass today reported a wide variety of snow surfaces including breakable crusts, icy surfaces, soft powders, wind textured slopes, and warm wet snow. With so many surfaces for the new snow to fall on, you could see the new snow react differently from one slope to the next. Often the crust layers were reported on southerly aspects and at lower elevations. 

Several recent avalanches were also reported, likely from the tail end of the last storm (Tuesday night). While on Friday these slides will be more than 72hrs old, they speak to the weaknesses found within the recent storm snow and wind-loaded slopes. We think avalanche activity will remain within the new snow Friday, but if you dig deeper you could possibly find lingering weak layers with the upper 2ft of the snowpack above the 2/3 interface. 

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