Bollettino valanghe

Snoqualmie Pass

Northwest Avalanche Center
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Pericolo valanghe

Fri
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

The snowpack remains wet and weak from recent rain. While avalanches are becoming less likely, if one occurs, it could grow very large and destructive. Limit the amount of time you spend on and under steep open slopes, especially when you see crevasse-like glide cracks.

Problemi valanghivi

  • Glide Cracks

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    2–3

    This week’s rain brought a massive amount of water all the way to the tops of most peaks around Snoqualmie Pass. You can tell just by listening to the roar of nearby creeks and waterfalls, that even though the rain has stopped, water is still moving through the landscape. As some of this water reaches the ground, it may cause natural glide avalanches where the entire season’s snowpack comes tumbling down. It can be nearly impossible to predict when these types of slides may occur. Fortunately, they frequently give an obvious clue as to where they might happen. Crevasse-like glide cracks can indicate the snowpack is on the move. Don’t linger on or under open slopes where you see these features. Even though these slides are becoming less likely, any glide avalanche may grow very large and destructive. 

    With a deep wet upper snowpack, it may be very hard, but not impossible to trigger a loose wet avalanche in steep terrain. If you get things moving, it will likely entrain significant amounts of snow and could grow large. These aren’t our normal little loose wet slides. If they catch you, they could kill you. Be very careful if you choose to cross open slopes greater than 35 degrees.

    (1/23/2022)

    Example: This very large glide avalanche is roughly 3m deep and ran to all the way down the N Slope of Chair Peak. 

    Photo: Dallas Glass

Avalanche Discussion

As of Wednesday afternoon, the Pass has received more than 9.5” of precipitation since Feb 26th, with more than 6” of that falling as rain. That’s a lot of water, and the snowpack shows the stress of the recent load. You can see debris piles from a widespread natural avalanche cycle on Monday, Feb 28th all around the mountains. These slides occurred on all aspects and elevations as temperatures warmed and rain reached high into the mountains. While many of these events were modest (D1-2), a few very large avalanches (D2.5-3) occurred on Chair Peak, Red Mt, and Cave Ridge. Some slides even crossed common travel routes. 

Now the snowpack is draining all that water. Many creeks are open and waterfalls are roaring. Runnels on the snow surface indicate that much of the water is working its way out. Snow profiles even show percolation channels (vertical paths for water) draining the surface. However, despite a thin breakable crust in some locations, the upper snowpack remains generally wet and weak. This likely won’t change until temperatures cool significantly and/or the skies clear allowing the surface to freeze solid. 

All the recent rain also created some very challenging and possibly dangerous travel conditions. Deep thick wet heavy snow, breakable crusts, open creeks, exposed rocks, and crevasse-like cracks all await you.

Regioni coperte