Bulletin d’avalanche

West Slopes Central

Northwest Avalanche Center
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Danger d’avalanche

Sat
Alpin
2 · Modéré
Limite forestière
1 · Faible
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

The first major storm in weeks will bring about a major change in conditions. Avalanche danger should remain low except for upper elevation terrain holding fresh slabs of wind drifted snow. Be ready to scale back your exposure to steep slopes as snowfall increases and unstable slabs form in downwind terrain. Stormy conditions could complicate travel in wind exposed areas.

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1–1.5

    Wind slab size and distribution should increase as new snow provides more raw material for the wind to blow around. Snowfall will pick up in the afternoon with a matching uptick in danger. Forecast wind speeds are strong enough that you might find fresh wind slabs in unusual areas, especially above treeline.

    Pay attention to wind direction and blowing snow - both will show you exactly which slopes are loading up. New slabs will likely be small and easier to avoid early on. Just steer around smooth, rounded drifts and other steep, wind loaded features. Heavier snowfall at day’s end could make for bigger slabs that require more caution in alpine terrain. 

    Active wind transport points the way towards fresh wind slab. 

Avalanche Discussion

Most precipitation with the coming storm should fall overnight Friday into Saturday. If heavy snowfall comes earlier than forecast, expect to find higher danger and reactive slabs in more areas. Danger at treeline would be more akin to Moderate than Low if this is the case.  Whatever ends up happening, be ready to scale back terrain choices and exposure in the afternoon. It will just get stormier as day turns to night.

Field reports were few on Thursday - most are likely waiting for the first major storm since mid-January to freshen things up. The passes saw temperature inversions that kept lower elevations cool with more warming higher up. The lack of recent new snow in the Central Cascades limited wet avalanche activity with no significant observations reported.

To the north, intense wind transport was noted on high alpine peaks. Wind slabs that formed in commonly traveled areas were easy to trigger but small in size. West Central is currently tracking less with West North and closer to the rest of the west slopes in terms of snowpack and recent weather. That will change with the coming storm as more snowfall is expected in this zone than those in the east and south.

Faceted layers - especially at the surface - are always on our minds coming out of an extended period of mostly high pressure. Various wind events, sun and warming, and bouts of light snowfall have probably prevented a uniform weak layer from developing across the zone. On the other hand, it’s better to know than speculate. If you are out tomorrow let us know what you find at the surface and even a bit deeper in the snowpack.

Régions couvertes