Bollettino valanghe

East Slopes North

Northwest Avalanche Center
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Pericolo valanghe

Wed
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
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Non aggiornato — questo bollettino è scaduto last year. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

With fresh snow and afternoon sunbreaks, wet avalanches will be the most likely problem to encounter. Watch for rollerballs as an indication to move to low-angle or shady terrain. In the northern and eastern parts of the zone, unlikely, very large avalanches on old snow should be a consideration at upper elevations. 

Problemi valanghivi

  • Loose Wet

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

    Fresh snow rests over slick crusts, and with sunbreaks in the forecast for tomorrow afternoon, this could quickly turn into a wet loose avalanche cycle. Wet loose avalanches often start from trees or rocks shedding snow onto the slope below, or you could trigger one on steep, sunny terrain. While these avalanches are more predictable than slabs, they have a lot of mass and can be difficult to get out of if you are caught. They could also run long distances on the underlying crust. 

    Pinwheels, rollerballs, and deep, wet snow all indicate that wet avalanches are possible. If you begin to see these signs, move to shady terrain or low-angle slopes. Overhead hazards from snow falling off rock slabs and cornice failures are also something to keep in mind. These monstrosities are hazards all on their own or could entrain wet snow as they move down slope, becoming a larger wet avalanche. 

    (3/17/2024)

    Wet loose avalanches that ran from steep rocks and cliffs in the sunshine. You might see conditions like this on Tuesday. 

    Photo: Willie Webster

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Unlikely
    Dimensione
    2–3

    If you're venturing into upper elevations east of the Cascade crest, take time to dig and look for potential weak layers in the top 3-4 feet of the snowpack. Stiff snow over softer snow layers deep in the pack is a key indicator of the potential for these consequential avalanches. When in doubt, choose more conservative, simpler terrain. 

    There is uncertainty surrounding older, weaker layers of snow. If you are in upper elevations or far east of the Cascade Crest, there might not be thick melt-freeze crusts over older weak layers. In these areas, east of Mazama and Hart's Pass, there may still be a chance of triggering persistent slab avalanches, where a shallower, weaker snowpack structure exists. 

    (3/17/2025)

    A widely propagating avalanche near Tiffany Mtn.

    Photo: Willie Webster

Avalanche Discussion

In the past 48 hours, there have been 5-8 inches of fresh snow, and the beginning of the storm brought strong ridgeline winds. This may have formed shallow wind slabs in steep, alpine terrain at upper elevations. We don't expect this problem to be widespread, but you should assess slopes for textured surfaces, drifts, or shooting cracks before committing to steep, extreme terrain where small avalanches can have high consequences. 

On Monday, WSDOT forecasters in the Highway 20 corridor reported easily triggered dry loose avalanches on steep terrain at mid and upper elevations. The crust from the previous warm temperatures was moist at lower elevations, getting more supportable at higher elevations. Over the past week, there was a well-documented wet avalanche cycle that likely started on the 24th and continued at least through the afternoon of the 26th. Many wet slides ran on a range of slopes, and some deeper slab avalanches were reported up to D3.

Before warming and rain, the January Drought Layer was buried 2–3.5 ft and shallower east of Mazama. Near Rainy and Easy Passes, the JDL was over 4 feet deep and capped with a thick melt-freeze crust. On March 17, an observer near Tiffany Mountain reported widely propagating recent natural avalanches and rolling collapses on a weak layer in the middle to lower half of the snowpack. As observations have become limited, our uncertainty about the snowpack has increased.

Submit an observation to the website or the Avy App to help NWAC Forecasters reduce uncertainty. It can be short, simple, and even anonymous. 

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