Bulletin d’avalanche

Mt Hood

Northwest Avalanche Center
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Danger d’avalanche

Thu
Alpin
2 · Modéré
Limite forestière
2 · Modéré
Sous la limite
1 · Faible
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Périmé — ce bulletin a expiré 2 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

Slabs will likely start the day as mostly small and manageable, but they will grow rapidly. As wind redistribution picks up, it’s important to assess how widespread the 6-inch or deeper snow deposits are above the crust or old snow interface. Heavy snowfall, strong winds, and subtle warming increase the risk of natural avalanches Wednesday night, so avoid all avalanche terrain after the sun sets.

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1–2

    Wind slabs may be larger and easier to trigger at higher elevations once you ascend above the 12/24 crust (found around 7000 ft). At these upper elevations more snow will be available for transport, along with sustained moderate ridgeline winds to move it around. Slabs at these elevations could exist in the typical spots below freshly corniced ridgelines, or down onto mid-slope convexities. Once you find wind deposits exceeding 6" on lee slopes, steer around slopes steeper than 35 degrees on wind-loaded slopes. These could be firm, punchy hard slabs or softer re-distributions. If the storm ramps up more rapidly than anticipated and you find widespread deposits greater than 6", consider retreating to lower elevations where avalanches should be smaller and easier to manage. 

     

    (1/11/2024)

    Example: Small shooting crack in wind drifted snow are a clear sign of instability.

    Photo: Joseph Dellaporta

Avalanche Discussion

Santa placed a slightly delayed order for Mt. Hood, but don’t worry—the white stuff will start stacking up as the day progresses, with this strong winter storm impacting the mountain Wednesday through Thursday! We're expecting 2-4" of snow by the end of the day with winds and snowfall rates ramping up. This storm comes on the heals of 1-2" of snow that fell on top of a 12/24 rain crust that exists up to 7000 ft. We have more uncertainty about the snowpack structure above this elevation but expect to find highly variable amounts of wind-redistributed dry snow above the solstice crust.

This is not your typical "moderate" avalanche danger day. The dynamic weather will lead to dynamic changes in the avalanche danger as the day progresses. Early in the day, you might find avalanches only on more isolated terrain features at upper elevations. By noon, you might find slabs on specific terrain features at upper elevations and on isolated features anywhere the 12/24 rain crust exits, and by the end of the day, you could find widespread danger and easily triggered slabs at upper elevations as the storm intensifies. 

A high elevation rain event on December 17th created a stout crust and resulted in a widespread avalanche cycle up to D3. This crust was subsequently buried by storms over the weekend (and reexposed by wind scouring). Focus your observations at and above this very prominent snowpack marker.  At lower elevations, the pack remains a bit thin. Watch for open creeks, bushes, and logs that make travel slow going. Rain could fall below 5000 ft or so on Xmas day, but it is unlikely to impact dry snow at these elevations.

Régions couvertes