Lawinenlagebericht

Central Cascades

Central Oregon Avalanche Center
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Lawinengefahr

Sat
Hochgebirge
3 · Erheblich
Waldgrenze
3 · Erheblich
Unterhalb
2 · Mässig
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Veraltet — dieser Lagebericht ist 2 years ago abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

Human triggered avalanches will be likely on Friday as heavy snowfall has arrived with strong winds from various directions. Pay attention to where the wind is blowing snow, and avoid steep, open, wind loaded terrain, using caution even at lower elevations. Sheltered slopes, such as treed areas, and low angle terrain (less than 30 degrees) will be your best bet for safe recreating as we give this new snow time to settle and stabilize.

Lawinenprobleme

  • Wind Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Likely
    Größe
    1–2

    It is not often we see a wind slab problem at all aspects and all elevations, but this is one of those instances where we may see wind slab formation in unusual areas, including lower elevations where open slopes are present. Recent snow has arrived with periods of strong to extreme winds from the Southeast, South, and West. Wind gusts of 80mph were recorded at 7800 ft on Thursday. These extreme winds are likely to load snow lower down on starting zones than you may expect. Varied wind directions, and the nature of certain terrain features to form wind tunnels could result in wind slab presence on any aspect. The few days of cold, clear weather that preluded this current swath of low pressure resulted in a variety of surfaces for the new snow to fall on. In many areas of the Central Cascades, a weak surface snow was observed Wednesday afternoon before precip began. Anywhere that wind slab has formed over weak snow will be easier to trigger. 

    Look for active wind loading by observing the direction wind is blowing snow off ridges, or along the snow surface. Avoid open, steep slopes on these leeward aspects. Textured snow surface is more likely to be scoured, or wind buffed, and will be a safer bet for travel. Use low consequence indicator slopes to test reactivity before committing to any steep terrain. Smooth, pillowed snow and shooting cracks under your skis will be an excellent indication of current instabilities. If in doubt, stick to low angle slopes less than 30 degrees.

Avalanche Discussion

Friday marks the first day that we have removed the Persistent Slab problem from the forecast. Since it's introduction to our list of avalanche problems, we found this PWL (1/31 buried facet layer) to be more pronounced on NW-NE aspects at near-treeline and below-treeline elevations. Recent observations show this layer being 4F density and becoming less reactive in stability tests, now sitting nearly a meter or greater below the snow surface. With no reported avalanche activity on this layer over the past week, it is currently on the far end of unlikely to trigger. That being said, a weaker snow structure is still there, and it is worth continuing to dig around to look for it's presence and reactivity in stability tests. We will continue to monitor this and provide any updates should conditions change and warrant increased caution.

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