Bollettino valanghe

West Slopes North

Northwest Avalanche Center
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Pericolo valanghe

Sun
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

Wind drifted snow will build unstable slabs on downwind slopes. There is a high level of uncertainty regarding the amount of new snow. Be ready to adjust your plan if you find 6" or more of new snow, shooting cracks, or signs of extensive wind transport like fresh cornices or deep drifts.

Avalanche danger ratings could be adjusted in the morning by 7:30 if needed.

Problemi valanghivi

  • Wind Slabs

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

    Gusty south and west winds continue to be the main ingredient in avalanche danger. There will also be enough new snow to spice it up and make avalanche conditions zesty - possibly tangy - on Saturday. Wind slab size and distribution are dependent on how much new snow falls overnight into the morning. If there is more new snow than expected plus strong winds, then prepare to find more and larger wind slabs, especially near treeline.

    Blowing snow and other visual clues should show you where fresh wind slabs lie in wait just below ridgeline on steep, leeward slopes. You may also find them farther downslope on cross-loaded features. Poor visibility could make wind slabs harder to pick out in the terrain around you. Monitor new snow depth you as gain elevation and change aspects. Use simple tests like hand shears and test slopes to see how well wind slabs are bonded to layers below - or simply bypass steep wind loaded slopes on lower angle, planar terrain.

    Example of shooting crack in a shallow wind slab.

    Photo: Dallas Glass

Avalanche Discussion

If new snow totals wildly exceed the forecast then danger from slab avalanches could extend into wind sheltered terrain, especially if temperatures rise abruptly in the afternoon. You may also encounter signs of instability like rollerballs and pinwheels with a rise in snow/freezing levels later on Saturday. Monitor changing conditions and remember avalanche danger can quickly increase during periods of intense snowfall or rapid warming.

New snow will fall on a variety of surface layers including sun crust, dry and weak snow in shady, wind sheltered terrain, old wind slabs, and wind scoured surfaces. Weak, faceted snow continues to be found around the Cascades at or near the current snow surface, sometimes above crust layers from the most recent atmospheric river event in early March. Besides the snow surface and new wind slab layers, the upper snowpack is generally strong with no current layers of concern. Human triggered avalanches on the Valentine’s Day crust and the late January crust-facet layers continue to be an issue in adjacent regions (East North and the South Coast and Sea-to-Sky zones in Canada). There were no reported avalanches in West North or Central associated with deeper layers since the natural avalanche cycle in late February/early March.

 

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