Bollettino valanghe

West Slopes South

Northwest Avalanche Center
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Pericolo valanghe

Fri
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
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Non aggiornato — questo bollettino è scaduto 4 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Blowing snow and actively wind-loading slopes should help you identify which features you want to avoid. While the storm may peak in the morning, as more snow falls, some of these newly forming slabs could grow large enough to bury or hurt you.

Problemi valanghivi

  • Wind Slabs

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

    Strong and gusty winds should easily form new slabs in a variety of locations Thursday. You could encounter wind-loaded pockets well below ridgelines, near exposed features, along the base of cliffs, and in confined gullies. Fortunately, figuring out where this hazard exists should be straightforward. Watch for blowing snow and take note of which aspects/features the wind loads with snow. Steer around these steep wind drifted areas. 

    While most of these wind slabs should stay relatively small, you may encounter larger avalanches on Mt St Helens, Mt Adams, and Mt Rainier where we expect more snow. As the day goes on, and more storm snow accumulates, you could see deeper slabs also develop in locations near Crystal Mt, and possibly White Pass.

    (12/3/2022)

    Actively blowing snow, freshly building sharp cornices, and textured surfaces. All easy-to-identify signs of wind-loading. Look for slabs to develop on the slopes on the left side of the picture.

    Photo: Dallas Glass

Avalanche Discussion

This flow pattern should favor the volcanoes and bring the highest snow totals to Mt St Helens, Mt Adams, and Mt Rainier. In these locations, the avalanche danger may peak during the morning hours with the brunt of the storm. Eight to ten inches of snow could fall by the end of Thursday. In other locations like Crystal and White Pass, it may take a bit of time for enough snow to accumulate to create a real hazard. In these locations, you may find the danger slowly rising as the day progresses. By the afternoon, you could see 3-8” of new snow. 

Observations from this week around the zone generally show a strong and well-settled snowpack. You may still see interfaces within the most recent storm snow, but a lack of avalanches and significant snowpack test results confirm these layers bonded well. In some locations, you can find weak sugary facets around the 11/22 crust. While Crystal Mt triggered a few avalanches on this layer last week, we have still yet to hear a report of a backcountry avalanche on these grains in this zone. So, while it’s not out of the question, the evidence seems to suggest a slide failing into older snow layers would be extremely unlikely. The common themes for this weak layer have been higher elevation (>6000 ft), rocky, and northerly terrain. 

Even with all the recent snow, early-season travel hazards still exist. Open creeks, holes near rocks, and thinly covered brush continue to hamper travel. Give yourself extra time to navigate these obstacles.

Regioni coperte