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
1 · Debole
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In sintesi

Avalanche danger will increase with elevation on Sunday. Avoid steep slopes where you identify recently wind-drifted snow, especially at upper elevations. Pay attention to increasing wind speeds and warming temperatures in the afternoon, and the effect they could have on snow stability.

Problemi valanghivi

  • Wind Slabs

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

    Strong wind gusts were recorded at the low-elevation Sedge Ridge weather station, and winds were quite strong in neighboring forecast zones. Winds should increase again Sunday afternoon ahead of the next storm.

    Wet snow and rainfall have likely reduced the amount of snow available for transport at low and possibly mid elevations, but higher up there should still be enough soft snow for fresh slab formation—in addition to wind slabs that formed in the last 24–48 hours.

    Drifting snow will be the clearest sign of active transport. Monitor snow depth and stiffness as you gain elevation and change aspects. If the wind isn’t blowing, look for cornices, scoured slopes, and other clues to identify slopes holding wind-drifted snow. You are much more likely to trigger an avalanche on slopes with recent wind loading.

    (3/8/2023)

    Example of smooth wind slab on the left and scoured snow on the right.

Avalanche Discussion

Low and mid elevations should generally be crusted over after rain and wet snow followed by overnight cooling. This should limit the effects of afternoon warming. If you find soft snow that could react to warmer temperatures, then watch for early signs of wet avalanche activity like rollerballs, snow shedding from trees, or very small loose snow avalanches.

The southern Cascades picked up another 0.5 to 1.5 inches of precipitation overnight, with the snow line pushing toward mid elevations in some areas. White Pass picked up another foot of snow by Saturday morning. The Bumping Lake SNOTEL topped out at 32°F overnight, while Green Lake—a higher but typically warmer location—hit 35°F before dropping quickly early this morning. Expect widespread crust at low and mid elevations.

Persistent weak layers active in late February and early March are thought to be nearing the end of their lifespan due to warming, additional loading, and time to gain strength. On the other hand, the last few days have delivered an exceptional load of snow and rain onto the existing snowpack. If you have good visibility today or tomorrow and spot any avalanches—large or small—let us know what you're seeing out there.

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