Bollettino valanghe

East Slopes South

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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Non aggiornato — questo bollettino è scaduto 2 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Warming temperatures and sunny skies will set the stage for wet avalanches along steep solar slopes. Move to shadier slopes once you notice rollerballs shedding or gloppy, wet snow under your feet or sled. Continue to look for pockets of unstable wind-drifted snow as you gain elevation. 

Problemi valanghivi

  • Loose Wet

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

    Freezing levels are on the rise and sunny skies are in forecast, increasing the likelihood of wet avalanches. You'll initially see signs of warming and wet avalanches beneath rock bands or on steep slopes with direct sun exposure. As the day progresses, you may notice signs of warming on east and west aspects as well. Most snow surfaces above 5000 ft have stayed dry and cold, so it won't take much for the snow to react. Rollerballs, pinwheels, or trees shedding snow indicate that surfaces are becoming wet and weak. Look for more shaded aspects once you start noticing these signs. 

    (3/7/2024)

    An example of small wet loose avalanches. Steep, cliffy, sun-exposed terrain is the first spot where you may notice wet loose activity. 

    Photo: Koby Yudkin

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–2

    Recent accumulations and a good dose of strong winds in the past days have built wind slabs along ridges and upper elevations across the zone. Expect these slabs to be thicker and more widespread as you gain elevation. You'll find more snow and larger avalanches further west, towards the Cascade Crest, particularly in the HWY 410 corridor close to Chinook Pass.

    Managing this problem is fairly straightforward. Be suspicious of any terrain features that promote drifting. You can typically find these on the downwind side of ridges, below cornices, and beneath rock and cliff bands. Using small test slopes or doing quick hand pits is a great way to gauge the reactivity of these slabs. If you notice blowing snow, textured rippled surfaces, hollow drum-like snow, or shooting cracks under your sled or feet, default to more sheltered lines. 

    (3/13/2024)

    Visual  clues help highlight where wind slabs may occur.

    Photo: Dallas Glass

Avalanche Discussion

While it may feel like spring in the valley, winter continues to linger in the mountains of the East South. This past week, trickles of new snow freshened up surfaces across the zone. You'll typically find 1-1.5 ft of recent snow resting over the stout crust left from last week's warm-up. Fortunately, this stout crust helped reduce the likelihood of triggering deeper layers of concern. However, you'll want to shift your focus to surface instabilities such as wind slabs or wet avalanches in the coming days. 

On Wednesday, an NWAC forecaster in the Ahtanum area found around 6" of new snow above 6000ft. New snow depths at lower elevations were significantly less, with rain down at the Snopark. A profile at approximately 6600ft on a NE aspect showed a stout crust below the recent snow. Shovel tilt tests produced moderate results with clean shears on this crust. In sheltered areas, there isn't much of a slab over this crust, but it could make wind slab avalanches easier to trigger. They also found the facets over the Early February Crust to be moist and rounded. This persistent weak layer is getting stronger and, combined with the stout surface crust, makes avalanches on this layer unlikely. However, there is always lingering uncertainty with these tricky, persistent weak layers, so step into large, north-facing alpine terrain with this in mind. A big warm-up or powerful storm could also bring this problem back to life. 

If you get out this weekend, let us know what you see by submitting a public observation here. 

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