Bollettino valanghe

East Slopes Central

Northwest Avalanche Center
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Pericolo valanghe

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

Where you find 1 foot or more of harder, more cohesive snow overlaying softer, sugary snow, you could trigger an avalanche large enough to bury you. Trigging an avalanche on a wind-loaded slope in the Salmon La Sac drainage is also possible. Look for red flags such as cracking, recent avalanches, and poor snowpack structure. To have a safer and more enjoyable day in the backcountry that doesn't tempt fate, steer around complex terrain and slopes steeper than 30 degrees.

Problemi valanghivi

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1.5–2

    This type of avalanche can break in surprising ways, wider than expected, and from flat terrain, but rollovers and convexities are prime terrain features for initiation. Areas where the setup for this problem exists will be closer to the Cascade Crest. Slabs will be particularly sensitive where the wind has made them deeper and denser on downwind slopes.

    As you move around the terrain, pay attention to the depth and cohesiveness of the new/recent snow. You're looking for the poor snowpack structure laid out in the Bottom Line. Cracking, collapsing (whumpfing), and recent slab avalanches are clear indicators that instability exists, but you might not see any before it's too late, which makes managing this problem tricky. When push comes to shove, you can just default to low-angle terrain free from overhead hazards.

    (2/3/2025)

    A skier triggered persistent slab avalanche near White Pass. This slide released over a 100ft wide and 2-3ft deep. WNW, 5600ft SS-ASu-D2-R2-O

  • Wind Slabs

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

    The Salmon La Sac will see another few inches of snow on Saturday, with some potential spillover from Snoqualmie Pass to make the totals even higher. Wind-loaded slopes are often found just below ridgelines and in cross-loaded gullies. Rippled, uneven snow surfaces and cornice development will point you toward where this suspected terrain is. Fresh slab development could overload slopes with poor snowpack structure, and a small surface avalanche could "step down" and become a larger and more consequential persistent slab avalanche. Actively blowing snow, cracks shooting from your equipment, or recent slab avalanches are signs of instability. If you see any of these, consider avoiding similar slopes steeper than 35 degrees.

    Payton triggered small, isolated wind slabs in the Blewett Pass area on Saturday. 

    Photo: Payton Schiff

Avalanche Discussion

We are moving further away from the initial heavy loading events that put the persistent slab problem on the forecast. However, we are working with a snowpack that is uniquely weak and abnormal to the PNW. Observers are still finding avalanches and other signs of instability throughout the forecast region, making it too soon to put total faith in a steep slope's stability when you otherwise might have. Give yourself wider safety margins and put together a conservative route plan for the day while we give the snowpack more time to heal. There is plenty of stellar (pun intended for the snow nerds out there) powder skiing and riding in on low angle slopes!

It's unlikely you will trigger an avalanche on south or west aspects, but keep in mind that there was a high level of variable surfaces prior to new snow falling. You could find a shadier slope that had weak snow form at the surface when it otherwise might not have under more normal circumstances. Regardless of where you choose to go, it is highly encouraged that you investigate for poor snowpack structure on a representative slope before jumping onto something steep.

Particularly near the Cascade Crest, you may encounter sluffs of dry loose snow in areas that have not seen direct sunshine. A small avalanche could knock you over and carry you into hazards such as rocks and cliffs. Be mindful of the terrain below you, and be prepared to manage your sluffs.

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