Bollettino valanghe

East Slopes South

Northwest Avalanche Center
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Pericolo valanghe

Mon
Alta quota
3 · Marcato
Limite del bosco
2 · Moderato
Sotto il limite
2 · Moderato
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Non aggiornato — questo bollettino è scaduto 5 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

You can still trigger large avalanches in areas where the wind has drifted deep slabs of snow. As you venture out on Sunday, choose conservative wind-sheltered terrain and avoid steep slopes near ridgelines, especially in alpine areas close to the Cascade Crest.

Problemi valanghivi

  • Wind Slabs

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

    Winds associated with this storm averaged 30 - 50mph with gusts of 60-90mph. These winds have likely built large slabs on various aspects, sometimes further down from ridges than expected. Identify and avoid wind-loaded areas by visual clues such as cornice formation or drifts around trees. Use your pole or probe to feel for areas of stiff snow over soft snow. If you observe these signs, stick to wind-sheltered terrain or avoid steep slopes.

    Use your pole or probe to feel for stiff layers over soft layers in the snowpack. 

    Photo: Katie Warren

  • Storm Slabs

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

    Moderate precipitation will likely linger in the southern Cascades. With cooling temperatures, it should build a favorable right side up snowpack. However, It may still be possible to trigger small avalanches in the new storm snow. It is always good to use simple snowpack tests, such as hand shears, to observe how the new snow bonds to the underlying surface.

    (12/9/2021)

    Quick, hand pits are a good way to gauge snowpack structure and upper snowpack instabilities.

    Photo: Adam Butterfield

Avalanche Discussion

A powerful storm moved into the region on Saturday, bringing significant precipitation, with rain up to 5600ft in some areas. The storm is forecasted to linger through Sunday in the southern parts of the Cascades. However, temperatures are expected to decrease, winds may taper off, and we could see a transition back to snow for many trailhead locations. While the cooler temps will help to stabilize any wet snow, higher elevations may still harbor storm snow instabilities. After a heavy-hitting storm such as this one, approach new terrain slowly, use hand pits to identify weak interfaces in the new snow and make observations frequently as you travel. 

While some areas of the East South zone still lack enough snow to produce avalanches, other areas have a significant and layered snowpack. We have little information and a lot of uncertainty about snowpack conditions near and above treeline. There is a lot of variability from north to south and east to west throughout the zone, and a more substantial snowpack exists in the northern and western portions. Expect that avalanche danger will vary, with increased danger in places close to the crest with a deeper snowpack. 

While we're excited about issuing daily forecasts for the East South zone this season, we need your help in making this successful. However and whenever you recreate in the mountains this winter, send us your observations.  - The team at NWAC    

 

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