Avalanche forecast

East Slopes North

Northwest Avalanche Center
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Avalanche danger

Sat
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
2 · Moderate
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Highlights

On Friday, you will be able to trigger avalanches in the new snow, especially where the wind forms deeper drifts at middle and upper elevations. Steer around steep terrain below ridgelines and on cross-loaded slopes. Avoid steep north aspects, especially those north and east of Mazama, where there is still a chance of triggering a very large, consequential avalanche in old snow layers. 

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2–3

    In the north and eastern portions of the zone, you may still be able to trigger large avalanches on an old, weak layer about 3 feet below the surface. The snowpack is shallower, and the layer is more well-developed near and east of Harts Pass and Mazama. Further west, near Washington Pass and Rainy Pass, these avalanches are unlikely.

    That said, the current gusty storms are adding enough stress to the snowpack that we can't write off persistent slabs altogether. You can deal with this low likelihood, high consequence situation by avoiding steep northerly slopes with shallow and variable snow cover in the eastern part of the zone. You can dig profiles and use snowpack tests (deep tap and propagation saw tests) to identify the weak layer. When in doubt, defer to lower-angle slopes and simpler terrain.

    (3/17/2025)

    A widely propagating avalanche near Tiffany Mtn.

    Photo: Willie Webster

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–2

    Friday will be another stormy day with up to 7" of new snow by the end of the day and plenty of southwesterly wind to form fresh slabs on leeward sides of ridges. Look for blowing snow and cornices that point to the wind-loaded slopes. Recent avalanches and cracks shooting out from your equipment are signs to avoid slopes steeper than 35 degrees. You can also use small wind-affected test slopes to observe how the snow reacts. If the snow fractures and slides easily, you could trigger an avalanche on a larger slope. 

    (3/18/2025) Recent natural wind avalanches in very steep terrain in the Eight Mile drainage.

    Photo: Will Govus

Avalanche Discussion

The past week and a half have been stormy, and Friday will be no different. Recent storms have totaled 2 feet near Washington Pass with less further east in the zone. On Thursday the 20th, observers on Silverstar Mtn reported natural wind slabs and loose dry avalanches at upper elevations. They triggered shooting cracks and observed southwest wind transporting snow at ridge tops. In the past week, observers have reported a number of small natural and triggered wind slabs avalanches. 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.

An old weak layer (the January Drought Layer) is buried 2–3.5 ft (70-120cm) below the surface but shallower east of Mazama. Near Rainy and Easy Passes, the JDL is over 4 feet deep and capped with a thick melt-freeze crust. In many parts of the zone, the weak layer has rounded and gained strength. In the past week, observers have continued to report snowpack tests that have produced sudden and propagating results on Silver Star Mountain and near Harts Pass. The signs of instability and much shallower snowpack (see profile below) near Tiffany Mtn indicate more dangerous conditions in the far eastern mountains.

NWAC Forecasters visited the site of the avalanche fatality near Harts Pass that occurred on 2/28. You can read the initial observation here. 

You can help us gather more data by submitting an observation HERE or via the Avy App. 

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