Bollettino valanghe

Snoqualmie Pass

Northwest Avalanche Center
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Pericolo valanghe

Thu
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 calendar may say April, but the mountains and the snowpack sure feel a lot more like mid-winter. You can still trigger avalanches within the recent storm snow, especially on steep convex rollovers, unsupported slopes, and wind-affected areas. With so much recent snow, any slide could easily grow large enough to bury and kill you.

Problemi valanghivi

  • Storm Slabs

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

    “It’s deep,” seems to be the most common phrase to describe the current conditions at Snoqualmie Pass. While this storm starts to draw to a close, and the danger slowly decreases, don’t forget about the immense amount of snow that fell since April 8th. With these cold temperatures, it will take a bit longer for this new storm snow to heal. Several weak layers can be seen in the upper snowpack, and any one of these could still produce a slide on the right slope. You’re most likely to trigger an avalanche near steep convex rollovers, on unsupported slopes, and in wind loaded areas. A quick way to investigate the upper snowpack will be to dig with your hand our shovel. Look for strong over weak snow and layers that fail easily. When you see the snow fracture suddenly, you’ve found the storm slab problem. While some of these slabs may be harder to trigger, with plenty of recent snow on the ground, any slide may grow quite large, especially on longer slopes.

    (4/12/2022) This shovel tilt test highlights one of several storm snow layers. Photo: Dallas Glass

Avalanche Discussion

It sure feels a lot like winter in the mountains. These recent cold storms brought more than 2 ft of snow at pass level, with nearly 3.5 ft at upper elevations since April 8th. By Wednesday morning, we may even add a few more inches to these already impressive totals. Needless to say, conditions are deep. On Tuesday backcountry travelers reported triggering one small storm slab in a steep north-facing couloir and many small loose dry avalanches on all aspects. NWAC staff, in nearby terrain, found similar conditions. All this recent storm snow rest over the very prominent 4/8 crust. You can use this snowpack marker to indicate how deep to dig and focus your observations on the upper snowpack. It can also help you locate deeper, wind -loaded and shallower, wind-stripped areas. Signs of wind-affected snow were evident on a variety of aspects Tuesday, but any wind loading seemed to be localized above 5000 ft. 

The sky continues to be the greatest source of uncertainty in the avalanche forecast. Given the time of year, it won’t take much in the way of sun breaks to cause natural loose avalanches. We’re expecting mostly cloudy skies, cool temperatures, and a stiff easterly breeze to help offset any short sunbreaks. However, if you see the sun come out for a significant amount of time, start to anticipate loose avalanches. Snow shedding from trees, rollerballs, and teardrop-shaped slides are all clear signs that the avalanche danger may be changing. Most of these natural avalanches will occur on steep sunny slopes. So, if you see these conditions develop, get off of and out from under this terrain.

Regioni coperte