Bollettino valanghe

Mt Hood

Northwest Avalanche Center
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Pericolo valanghe

Tue
Alta quota
3 · Marcato
Limite del bosco
3 · Marcato
Sotto il limite
2 · Moderato
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Non aggiornato — questo bollettino è scaduto 5 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

You are likely to trigger a wind slab on open slopes steeper than 35 degrees near and above treeline as winds continue to move snow during the day. Wind slabs may have formed in unusual locations and further below ridgelines than usual.  You may encounter storm slabs or wet loose avalanches on very steep slopes in wind-sheltered terrain at lower elevations. 

Problemi valanghivi

  • Wind Slabs

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

    Extreme west winds will become more northwesterly Sunday night into Monday.  With 6-12" of fresh snow to move around,  it's not a question of if but whether where wind slabs will form.   NW winds are known to cause unusual loading patterns.  The strength of the winds may have formed them further downslope than you'd normally expect or even on open slopes below treeline.  This will be a tricky day to travel in and around wind-affected avalanche terrain.  Avoid open slopes steeper than 35 degrees where you find freshly drifted and wind-stiffened snow.  

    Give cornices a wide berth as you travel along ridgelines and be aware of the overhead hazard if traveling on slopes below large cornices. A cornice fall could trigger a slab avalanche on the slope below.

    Example from Mt Hood earlier this month. Winter returned Sunday night. Watch for shooting cracks in wind-stiffened snow. You may trigger a wind slab on nearby slopes.

  • Storm Slabs

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

    In wind-sheltered terrain below treeline, you may trigger a storm slab on convex rollovers and very steep unsupported slopes where you find 6" or more of new snow.  On the west side of the mountain where more snow is expected, storm totals may be closer to a foot of snow.  Use can use small test slopes to gauge how the new snow has bonded to the old snow surface (likely the 3/28 melt-freeze crust).  

    Clouds and cool temperatures should keep the wet loose avalanche potential largely in check Monday.  However, the days are long and sunbreaks are likely on the east-side of the mountain.   If and when the sun breaks out in your part of the mountain,  the potential for wet loose avalanches will rise on very steep sunny slopes.  Wet loose avalanches may release naturally below steep rock faces that catch the sun.  If you see pinwheels or rollerballs,  or find yourself sinking into wet surface snow more than ankle deep,  move to lower angle or a shadier terrain. 

    Example storm slab from February at Bennett Pass.

Avalanche Discussion

Prior to this storm, observers at Mt Hood on Saturday reported wind-packed snow surfaces near and above treeline.  Wind slabs that were triggered earlier in the week were no longer reactive.  

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.

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