Bulletin d’avalanche

East Slopes Central

Northwest Avalanche Center
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Danger d’avalanche

Tue
Alpin
2 · Modéré
Limite forestière
2 · Modéré
Sous la limite
1 · Faible
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Périmé — ce bulletin a expiré 5 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

Fresh wind slabs will form on lee slopes near and above treeline Sunday night.  Steer around steep open slopes where you find firmer wind-stiffened snow.  Slabs may be larger and more consequential near the Cascade crest where more snowfall is expected overnight. 

Problèmes avalancheux

  • Wind Slabs

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

    Strong westerly winds will transport new snow onto lee slopes Sunday night and Monday.  Winds may transport new snow further downslope or below ridgelines than usual.  While most wind slabs will likely be shallow,  deeper slabs are likely to build closer to the Cascade crest.  As you travel, look for blowing snow along ridgelines, spindrifts loading slopes below cliff bands, and feel for textured wind-affected snow as you change aspect and elevation.  All of these signs will help you identify which slopes to steer clear of on Monday. 

    If traveling along ridgelines with large cornices make sure to stay well back from the edge.  Travelers are surprised every season when cornices break further back than they expect.  Cornice fall could trigger an avalanche on the slope below.

    Example of a shallow wind slab in the Wenatchee Mountains.

Avalanche Discussion

6+ inches of new snow may accumulate near the Cascade crest, especially downwind of Snoqualmie Pass tonight through Monday morning.  New snowfall amounts should taper off for areas further east and north of Hwy 2.  Strong westerly ridgeline winds are expected to be widespread and last for the better part of Monday across the zone.  While wind slabs are the main avalanche problem to keep on your radar,  there will likely be substantial sun breaks further east of the Cascade crest.  It's spring-time, so if the sun pops out for an extended time following new snowfall, expect wet loose avalanches to follow suit on steep sunny slopes.  If you are sinking into wet surface snow deeper than your ankle or you see rollerballs or pinwheels release naturally on sunny slopes, it's time to change aspect or move to lower angle terrain.  

A crust and adjacent weak layer formed in mid-January can still be found about 2-6 feet below the surface throughout most of the zone.  Several different avalanche cycles released down to this interface, with the last cycle producing avalanches up to size D4.  Avalanches down to this layer are now unlikely with the last known avalanche down to the mid-Jan crust/facet combo recorded on March 1st.  We're watching the upcoming weather pattern for major warm-ups or storm events to see when and if these deeper layers will be tested again. The most suspect areas for deep persistent slabs are shallow, rocky, and unsupported slopes, especially where overhead cornice fall could trigger avalanches.

Régions couvertes