Bollettino valanghe

East Slopes Central

Northwest Avalanche Center
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Pericolo valanghe

Thu
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
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In sintesi

Expect increasing danger during the day, with shallow but touchy wind slabs forming on exposed slopes. Look for active wind transport, textured surfaces, and shooting cracks. Steer around slopes steep enough to slide if they appear to be drifted over.

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–1.5

    Weak snow and strong winds are a great combination for wind slab avalanches. We'll have that on Wednesday. We got a taste of what this could be like on Monday, when parties reported easily triggering wind slab avalanchesin adjacent zones. Easterly winds will increase during the day, so we can expect an increasing amount of snow transport during the daytime. Slabs could be quite reactive as they build over very weak and faceted surfaces.

    Pay attention to how the snow changes as you travel. Look for textured surfaces, and active transport. Look for cracking with wind stiffened snow. Steep slopes beneath ridgelines, cols, and other open, exposed slopes may be the most likely locations you'll stumble into these. Look for drifting to occur even below treeline especially in the afternoon in areas exposed to East/West oriented valleys.

    (1/2/2023)

    Small, ski triggered hard slab avalanche near Crystal Mountain. 

    Photo: Barrett Gray

Avalanche Discussion

We're beginning a pattern that should slowly add snow to the zone with wave after wave of upslope flow. For Wednesday, south easterly winds will accelerate through valleys on the east side of the Cascade Crest like the Teanaway and Icicle. The few days of colder temperatures have weakened snow surfaces, and surface hoar has grown large in many areas. In some areas, the snow could be so weak that it runs as a dry loose avalanche on steep slopes. In others, a rain cruts may sit atop surfaces. Katie and Josh reported this and rimed surface hoar with to ridgetop in the upper Icicle on Tuesday. On Wedge Mountain on Monday these feathery crystals were larger than 1 inch in many areas, and found on east and northeast aspects from 4,000ft up to 6,500ft. Southeast to southwest aspects had a sun crust, and consistently had a layer of surface hoar on top. At lower elevations in the Salmon la Sac, observers have been reporting firm travel on an ice crust. Ridgelines have been experiencing light drifting from both east and westerly winds, and Andy found a double cornced ridge near Sasse Mtn on Sunday. On Saturday, avalanche workers at Mission Ridge triggered cornices and small wind slabs with explosives. 

On average, you could expect about 8-18 inches of new snow resting on the Christmas Crust at mid and upper elevations, and north of Blewett Pass even at low elevations. In the further eastern parts of the zone there may be less. Expect to hit this 'bottom' in many areas, and travel could be very slick and slippery, especially on steep slopes. The crust takes the form of an impenetrable ice lens from many hours of freezing rain up to about 4,500ft in the zone. At higher elevations and near the crest, the crust is more opaque and breakable, and may be covered with more snow. In both cases the snow above this crust is weakening and faceting, so it'll be worth monitoring as more storms eventually make their way into the region.

If you make it out to enjoy the mountains, consider submitting an observation!

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