Bulletin d’avalanche

West Slopes North

Northwest Avalanche Center
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Danger d’avalanche

Mon
Alpin
2 · Modéré
Limite forestière
2 · Modéré
Sous la limite
1 · Faible
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Périmé — ce bulletin a expiré 4 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

Terrain features with wind drifted snow are where you are most likely to encounter an avalanche on Saturday. Identify slopes with smooth, wind buffed surfaces or pillow-like piles of snow, particularly on convex slopes where triggering an avalanche is more likely.   Fall back to simpler terrain if weather and avalanche conditions make for more hazard than expected. 

5:55am update:  Wet avalanche activity should still be an issue on Sunday with snow levels hovering near treeline. Pay attention to slopes overhead and look for signs of instability like pinwheels, rollerballs, or snow shedding from trees and rocks. Also look for glide cracks, cornices, or other unstable snow features. Don’t linger directly under steep slopes where you see any of the above. 

Problèmes avalancheux

  • Wind Slabs

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

    Moderate winds - increasing to strong in the afternoon - will continue to build slabs with any fresh snow accumulating Sunday. Wind slabs are usually found just below ridgelines but you may see them in more sheltered terrain if winds are very strong. You could also find larger, more reactive slabs as you gain elevation to where there is drier snow.  

    Actively loading slopes should be fairly obvious. Also pay attention to wind affected snow surfaces and changes in snow texture to identify slopes with wind slab. Evaluate new wind slab layers using simple tests - hand shears, test slopes, skin track tests, etc.

    If you experience heavy snowfall be ready to find unstable slabs in all steep terrain, not just in wind loaded areas. Downshift to a more conservative plan if you find conditions different (as in more snow, stronger wind, etc.) than anticipated. 

    (1/7/2023)

    A human triggered wind slab avalanche that was reported today from near Mt. Rainier. Similar avalanches are possible in West North tomorrow. 

    Photo: NWAC Public Obs

Avalanche Discussion

Yet another warmer-than-expected system moved through the area Saturday and dropped a quarter to a half inch of precipitation across the zone. Dry-ish snow was found above 4800’. Rain was again a fact of life below treeline. Multiple days of near-freezing temperatures have left large cornices sagging. Minimize time spent below these monsters. 

Nobody has been raving about snow quality the last few days but redeeming riding conditions can probably be found. Comments like “there's a few inches of cream cheese with a hint of zipper crust up high” or “it was glue-like but not sticky” might be the best way to describe the snow surface at different elevations.

No new avalanche activity was reported in West North on Saturday. The day prior brought a report of a naturally triggered slab avalanche that likely occurred early Friday morning (judging by the bit of new snow over the debris). It appears to be triggered by sluff or cornice fall from above. A few small wet avalanches were reported as well the same day.

There is currently 1-3’ of snow over the rain crust buried in late December. The upper snowpack is reported as well bonded with no layers of concern.  Instability has been limited to the most recent new snow and wind slab layers.

Régions couvertes