Bollettino valanghe

Stevens Pass

Northwest Avalanche Center
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Pericolo valanghe

Sat
Alta quota
3 · Marcato
Limite del bosco
3 · Marcato
Sotto il limite
2 · Moderato
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Non aggiornato — questo bollettino è scaduto 5 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Significant snowfall and strong wind have created dangerous conditions that could linger through Friday.  Expect to be able to trigger large avalanches on open, exposed areas where wind has created thicker slabs. Avoid steep slopes if you find any signs of instability such as shooting cracks and recent avalanches. 

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    2

    You'll find leftover slabs from Thursday/Thursday night as you gain elevation. These could be tricky, as wind slabs sometimes are. Slabs could be disguised underneath recent snow that fell without wind. Look and feel for thicker drifts, textured surfaces, and shooting cracks. You are most likely to trigger one on steep slopes near and above treeline in exposed locations, such as the leeward sides of ridges and gully edges. Avalanches could be larger at upper elevations, where there is more snow and drifts are deep.

    Avoid suspect-looking areas and likely starting zones such as convex rolls and pillowed snow on steep slopes. Stay off of steep slopes altogether if you find evidence of instability such as shooting cracks or the snow feels hollow or punchy.

     

    (12/23/2021)

    Wind slab on a small slope. E aspect at 5,400ft.

    Photo: Matt Primomo

  • Storm Slabs

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

    If you enter a steep slope, expect that you could trigger an avalanche. Soft storm slabs and sluffs were easily triggered on Thursday and may continue to be reactive on Friday as snow continues to stack up. You are most likely to trigger a small, soft slab on very steep and unsupported features, such as convex rollers. Use test slopes to evaluate how the new snow is bonding as the day progresses. If its not a slab, it could be a loose dry avalanche. If you choose to enter steep slopes even outside of wind affected areas, travel defensively, as these slides could gain momentum and run far.

    (12/20/2021)

    Example small storm slab, near Highway 20 in the East North zone.

    Photo: Adam Butterfield

Avalanche Discussion

We've been in a storm cycle since the Solstice, and the snow just keeps adding up. Another 12" accumulated at pass level on Thursday, and more is on the way. Storm totals are quickly approaching two feet. Expect another round of similar amounts of snowfall into Friday, with even colder temperatures. Winds were strong and moved snow easily on Thursday. A thin melt-freeze crust was buried late on the 21st and could be found a couple feet beneath the snow surface. Observers noted how the snow felt hollow and localized collapsing was observed beneath this crust.

On Thursday, numerous observers reported triggering avalanches easily. Slides were larger at higher elevations where wind created thicker slabs. The snow is getting deep, and it's time to stay away from tree wells and consider the dangers associated with deep snow immersion safety. Trees have also been toppling over under the weight of the heavy snow. Keep your partners nearby in these conditions.

The lower snowpack is gaining depth and is generally strong. A number of crusts may be found in the lower snowpack, although they aren't expected to be problematic for avalanches. A pair of crusts from late November/early December can now be found 4-5 feet below the surface.

Regioni coperte