Bollettino valanghe

West Slopes North

Northwest Avalanche Center
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Pericolo valanghe

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

In sintesi

Rain in most areas fell as snow in the alpine. Identify and steer around steep slopes holding wind-drifted snow at upper elevations. Thick layers of wet or crusty snow can make for challenging travel, especially in areas with minimal snow cover.

Problemi valanghivi

  • Wind Slabs

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

    While precipitation fell as rain in most areas, up to 1’ of new snow will accumulate at upper elevations. And winds were strong enough to drift this snow into fresh slabs. Decreasing wind speeds should put an end to active loading by Sunday.

    Note changes in new snow depth and stiffness as you gain elevation and change aspects. You are most likely to find fresh wind slabs on leeward slopes just below ridgeline. Scoured and textured snow surfaces can help you figure out which slopes could be loaded up with wind slab.

    With lowering snow levels overnight, there should be a few inches of new snow at mid-elevations. It probably won’t be enough to increase avalanche danger but still worth keeping track of in case we get more snow than forecast.

    Use small wind-loaded features along ridgelines to hunt down wind slab.

Avalanche Discussion

A cooling trend into the New Year should reduce any lingering instability at low and mid-elevations where warm temperatures and manky, wet snow have dominated for days. Yet upper-elevation slopes  - the terrain that picked up the most new snow - could produce rollerballs and even a few wet avalanches with solar warming. Keep an eye on steep, south-facing terrain overhead if the sun makes an appearance.

Observers around the Baker BC on Saturday reported wet, rainy conditions. No new avalanche activity was noted despite overnight temperatures well into the 40s and continued rainfall. There was however a new glide crack at mid-slope on the north aspect of Table Mt.  Heather Meadows saw 0.65” of rain by mid-afternoon. Other weather stations around West North reported about half that amount of rain.

The day prior, a team in the Hidden Lake Peaks area found wet snow up to 6000' with pockets of drier, wind-drifted snow above that elevation. They were able to trigger a small loose wet avalanche in alpine terrain.  

A thin, well-consolidated snowpack that’s seen significant water is found in many parts of West North. At mid-elevations, it consists of alternating layers of melt forms and crusts from surface to ground. Snow depth averages 2-3’.

You might find a drier, more layered snowpack at upper elevations and also farther east in the zone (Cascade Pass, Ruby Mt, etc), that likely saw less rain and slightly cooler temperatures. If traveling up in the alpine or near the Cascade Crest, prepare to make your own observations and adjust your plan as necessary.

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