Bollettino valanghe

Olympics

Northwest Avalanche Center
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Pericolo valanghe

Sat
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
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In sintesi

Even though we aren’t expecting too much new snow in the Olympics, winds should easily build new slabs on the lee sides of ridges and along the base of cliffs. Look for blowing snow, fresh cornices, and sharp drifts to help you anticipate wind-loaded slopes before you commit to a higher consequence slope.

Problemi valanghivi

  • Wind Slabs

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

    You should find fresh pillow-like drifts in some unusual places Friday thanks to the NW-N winds. So, don’t expect to follow your normal travel patterns. Take time to look for clues like blowing snow, rime, and textured surfaces to help you anticipate wind-loaded features. You’re most likely to see small wind slabs in the tops of chutes, near the base of cliffs, and under sharp cornices. While we expect these slides to stay relatively small, some of them could sit over a firm crust. This may allow them to trigger very easily and travel quickly. Don’t let one of these slides take you for a ride down a couloir or over a cliff.

Avalanche Discussion

This seems like a pretty simple equation. New snow plus moderate winds equal wind slabs. However, we don’t know much about the state of the snowpack in the Olympics. There are really two big questions to answer. 

1: How is the new snow bonding to the old surface? 

2: Are there any older layers in the upper snowpack that could also fail? 

This first question should be easier to test. Small slopes and hand pits will allow you to take a quick look at the new snow and how it’s sticking to the old surface. With cooling temperatures, we’re generally expecting the new snow to form right-side-up in sheltered terrain. While this could result in a few small sluffs, it should limit slab avalanche activity. However, firm crust, surface hoar, and facets could all exist at this interface and change the equation. 

Understanding the upper snowpack, however, is a bit more daunting. The amount of snow over the very prominent MLK crust varied widely prior to this storm. It’s hard to say how this snow fared over the past week. You’re most likely to find weak snow layers on slopes that don’t receive direct sunshine and where this overlying snow is thinner. The only way to really tell is to look for signs of recent avalanches and take time to dig. Fortunately, this storm should be a fairly light load, and not stress these older layers too much. If you see slides running on the icy MLK crust, the scales may have tipped and it’s time to dial it back.

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