Bollettino valanghe

Mt Hood

Northwest Avalanche Center
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Pericolo valanghe

Sun
Alta quota
3 · Marcato
Limite del bosco
3 · Marcato
Sotto il limite
2 · Moderato
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Non aggiornato — questo bollettino è scaduto 6 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Wind drifts will become large and reactive to human trigger. Avalanche conditions will deteriorate drifts continue to grow atop low-density and potentially weaker snow layers. Avoid all slopes steeper than 35 degrees where you see signs of active or recent wind-loading.

Problemi valanghivi

  • Wind Slabs

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

    Friday's deep, unconsolidated low-density powder will turn into Saturday's wind slabs with the help of moderate SSW winds and an additional 5-10" of fresh snowfall.  Avalanches are expected to be widespread and could be large at higher elevations or in isolated cases where they step down to weak snow above the 1/13 crust.  Firm layers with soft snow underneath, settlement under your feet, whumps, and shooting cracks are all signs of instability that remind you to dial back your terrain selection.  Avoid all wind-loaded slopes steeper than 35 degrees.

    Example: Wind textured snow surfaces and drifts like these serves as great clues that the wind affected the snowpack and may have formed wind slabs on nearby slopes.

  • Loose Dry

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

    If you find wind-sheltered terrain, you may continue to the excellent conditions found at all elevations on Friday. However, on slopes 40 degrees and steeper, dry snow will move as an unconsolidated mass. These should be mostly small, but could grow large enough to bury you, entraining the full 20" or so of snow above the crust.  These avalanches are most dangerous where they involve a terrain trap, potentially pushing you into a gully or over a cliff.

    (1/28/2021) Example: Small Loose Dry Avalanche on steep slopes.

Avalanche Discussion

Mt. Hood meadows found only very minor avalanche reactivity on Friday, limited to shallow pockets on NE aspects. Notably, the snow was unusually dry, dense and not wind-affected. That is all set to change on Friday night into Saturday as a fresh round of snow and wind arrive.

Prior to the incoming storm, the mid-elevation upper snowpack averaged 10-15" above the stout mid-January crust. Snow arrived in several installments over the course of the week. The most recent 2-4" of snow fell Wednesday night with light winds. A slightly more significant event (4-9") arrived Tuesday night, but an uncommon SE wind pattern means the distribution of older wind slabs is not typical. The eastern side of the mountain received more snow than the western slopes and the north side of the mountain received some of the stronger winds Tuesday night.  However, wind slabs from Tuesday night are growing old and are now of far less concern than fresh wind slabs. The stout mid-January crust is considered the new "ground" moving forward with a strong snowpack structure in place below this layer. 

Weak facets identified above the 1/13 crusts were the likely culprit in a significant whumph observed around 7000 ft on a N aspect on the Cooper Spur.  We expect a pattern of recurring avalanches on this layer until a warmer storm brings snow to bond to this old icy surface.  

During the ongoing Covid-19 pandemic, continue to follow the latest guidance from local, state, and federal health officials. Avoid unnecessary risks that could impact first responders and stress medical resources.  Wear a mask when appropriate, practice social distancing, and consider recreating closer to home.

Regioni coperte