Bulletin d’avalanche

West Slopes South

Northwest Avalanche Center
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Danger d’avalanche

Sun
Alpin
3 · Marqué
Limite forestière
3 · Marqué
Sous la limite
1 · Faible
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Périmé — ce bulletin a expiré 3 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

An approaching storm will develop more dangerous conditions at middle and upper elevations on Saturday. Increasing winds should easily drift snow into firmer and thicker slabs.  Watch out for steep slopes below sharp drifts and areas of blowing snow.

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    1–2

    You’ll need to manage 2 different wind slab problems on Saturday. Slightly older wind slabs from Thursday night produce a natural and several small skier-triggered avalanches Friday near Crystal. These slabs often hid under a few inches of soft snow. Drifts and the snow blown out of nearby trees were the clearest clues they were present. 

    Increasing and shifting winds on Saturday should build a fresh batch of wind slabs. Expect them to grow larger and possibly more reactive throughout the day. Blowing snow will probably be the easiest observation to indicate local wind patterns and which slopes are actively loading. 

    Wherever you see these wind slab clues, steer around nearby steep open slopes.

    This was one of three small human triggered wind slabs observed in the Crystal Backcountry. 

    Photo: Shane Robinson

Avalanche Discussion

The incoming storm Saturday will create dynamic conditions. You’ll probably see the greatest avalanche danger later in the day. As the storm intensifies and warms overnight, very dangerous avalanche conditions should develop. This could include a large natural avalanche cycle extending into Sunday morning.  

Winter returned to the mountains Thursday. Since then 1-2 feet of snow accumulated at mid-elevations across the zone. Friday, NWAC forecasters and avalanche professionals near Crystal Mt and Paradise reported minor storm snow layers and a generally good bond to the old rain crust (12/6). Avalanche concerns were mostly limited to wind-drifted areas. 

While the new snow definitely helped travel conditions, the snowpack is still quite thin at lower elevations. This should limit the avalanche hazard in these areas. However, rushing creeks, open holes, shallowly buried rocks, and plenty of scrubs/trees still make travel tricky. Take it slow and give yourself time to deal with these early-season hazards.

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