Bollettino valanghe

East Slopes Central

Northwest Avalanche Center
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Pericolo valanghe

Sat
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. It is also possible to trigger small loose avalanches of low density snow that can knock you over and carry you into hazards such as rocks and cliffs. For 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, such as the Salmon La Sac drainage. Slabs will be particularly sensitive where the wind has made them deeper and denser on downwind slopes. 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.

    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

  • Loose Dry

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

    All of this new and recent snow lacks bonding and cohesion where it's staying cold and sheltered. Expect to see sluffs of dry snow anywhere throughout the zone, but this problem is more apparent closer to the Cascade Crest. Dry loose avalanches start at a point and entrain more snow as they move downhill and fan out. Be mindful of terrain traps below you and avoid this problem by manuevering around steep rollovers or gullies.

    (2/4/2025)

    A small skier triggered dry loose avalanche on a north aspect at 3400'. It ran 100 ft and entrained snow below the 01/10 crust.

    Photo: Nate Hough-Snee

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. It is still too soon to put total faith in a steep slope's stability when you otherwise might have in areas where this problem exists. 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) skiing and riding in "cold smoke" pow on low angle slopes!

It's unlikely you will trigger an avalanche on southerly 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.

With all of this soft, dry snow, it won't take much for it to get picked up by even light wind. Don't rule out the possibility of encountering a fresh wind slab avalanche. Wind-loaded snow could be found at upper elevations on all aspects, but you are more likely to find thicker slabs and cornice development on northerly slopes. Similar signs of cracking and recent slab avalanches will indicate instability.

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