Bollettino valanghe

West Slopes South

Northwest Avalanche Center
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Pericolo valanghe

Wed
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
2 · Moderato
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In sintesi

The weather will shift on Tuesday from wet and stormy to dry and potentially sunny. As a result, you’ll need to manage changing avalanche conditions. Pay close attention to the terrain around you and use caution if your travels take you to places where even a small slide can push you into a creek or over a cliff.

Problemi valanghivi

  • Loose Wet

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

    We think there will be enough sunshine on Tuesday to cause the new snow to become wet and unstable on steep southerly slopes. This should mainly result in lots of new roller balls. However, there's enough new snow (especially in the near treeline band) to produce real loose wet avalanches. Fortunately, these are easy to predict and manage. If you see long periods of sunshine, rollerballs, or other small loose slides, expect loose wet avalanches on nearby sunny slopes. Pay attention to the slopes above you, and don’t let one of these small slides push you into a creek or over rocks.

  • Wind Slabs

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

    While not the most in-your-face issue Tuesday, wind slabs could certainly be the most hazardous. Very strong and gusty winds the past several days likely formed pockets of wind-drifted snow along exposed ridges, in confined chutes, near the base of cliffs, and on cross-loaded gullies. Look for textured snow surfaces and drifts to help you anticipate wind-loaded features. When you see smooth pillow-like drifts go around them by seeking out lower angled slopes. We expect most of these slabs to remain small and easier to manage. However, if you head into higher-elevation terrain you could encounter larger and firmer slabs that may break above you making them particularly dangerous.

Avalanche Discussion

The West South zone could pick up another inch or two of snow Monday evening before the precipitation tapers and winds decrease. This will bring an end to our recent active weather pattern that began around Jan 4th for most locations. The biggest source of uncertainty in this forecast is the sky. Clouds are notoriously hard to forecast post-storm. So, if you find yourself socked in with poor visibility, you might not see a loose wet issue. 

Recent storms impacted different areas in the zone at different times. However, the general storm totals since Jan 4 have been about the same. You’ll often find 8-14 inches (20-35cm) over the 1/4 interface. Buried surface hoar was observed at this layer at White Pass and Mt Hood. While no other confirmed observations have been reported, observations this weekend from the Paradise area did note the snowpack failing at depths that would correspond to this layer.  You can take time to dig with your hand or shovel to look for this potential weak layer. Below the recent snow, a very strong and settled upper snowpack is well bonded to the Christmas Crust. This prominent snowpack marker is easily identified 2-2.5 ft (60-75cm) below the snow surface. At present we believe avalanche activity should remain within the most recent snow above the 1/4 interface.

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