Bollettino valanghe

West 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 4 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

UPDATE: Decreased danger and removed the storm slab problem due to lack of snowfall overnight. 

Certain areas of the West South zone will get enough new snow to create heightened avalanche conditions, especially in areas where the wind drifts the snow deeper. You could trigger larger slides near ridgecrest, in chutes, or along the base of cliffs. Steer around steep slopes where you find smooth pillow-like drifts.

Problemi valanghivi

  • Wind Slabs

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

    No matter where you are in the zone, strong winds will be the biggest contributor to the avalanche hazard. Even if you don’t find much new snow, expect the wind to have significantly loaded the lee sides of ridges and exposed features. Blowing snow, fresh cornices, and sharp drifts will all point towards aspects where you may find potential wind slabs. In some areas, these slabs may be simple bright white pillow-like drifts you can just go around. However, in other places, you could find large wind slabs that span wider across the feature, chute, or bowl. One thing that could make this setup unique is the presence of an underlying crust. You may find some avalanches trigger very easily and run quickly. 

    Unless you are certain you can avoid the small wind pocket, best to give all steep wind-loaded slopes a wide berth. In locations that receive more snow, some of these potential avalanches maybe 2ft thick and could easily take you for a nasty ride and even bury you.

    (1/29/2023) This NE-E facing blowing is normally full of snow, but with this wind pattern, it is stripped down to old crust layers. Photo: Dallas Glass

Avalanche Discussion

While not a particularly impressive storm, many areas of the zone could receive 6-12in of snow by Saturday afternoon. Expect dangerous avalanche conditions in locations on the higher end of that snow total (Paradise, Mt St Helens), with lower danger in places that see less snow. 

One big question we have heading into the weekend is the new 2/3 interface. In many places, this presents as a crust of varying thickness. However, more interestingly, on some slopes, sugary facets and/or feathery surface hoar were reported. Because of the variability in the surface prior to this storm, you may find that the snow responds differently from one slope to the next. Use lots of moving observations like hand pits, uptrack tests, and small slopes to see if the new snow fails under your weight. 

With warming temperatures Saturday, thinning clouds, and maybe a little rain, you could see small loose wet slides at lower elevations. In general, we expect this to be primarily a rollerball event, but in some places, more legitimate avalanches could occur. If you see new rollerballs or small point-release slides, expect similar avalanches on nearby slopes. 

Right now we are primarily concerned with avalanches occuring at or above the 2/3 interface. However, we continue to find lingering old layers/interfaces in the upper snowpack. Some of these routinely fail in snowpack tests. This storm shouldn’t be enough to wake them up, but we are still monitoring the upper snowpack (~2-3ft) above the prominent MLK crust.

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