Avalanche forecast

Mt Hood

Northwest Avalanche Center
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Avalanche danger

Wed
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
2 · Moderate
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Out of date — this forecast expired 6 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

 Avalanche hazard will rise throughout the day as new snow arrives Tuesday falling onto weak snow surfaces with a firm crust underneath. You will be able to trigger an avalanche large enough to bury you in steep terrain where winds have drifted the snow or in the afternoon when the temperatures rise and more snow has accumulated. 

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–2

    Strong WSW winds will accompany fresh snow and rising temperatures Tuesday. This new snow will be wind transported to soft and weak snow surfaces that rest above a firm melt-freeze crust. You will likely be able to trigger a wind slab on lee slopes steeper than 35 degrees especially later in the day as more snow accumulates and temperatures warm slightly. Identify slopes where wind deposited snow is accumulating and navigate around them. Use cornices, pillow-like drifts, and cracking in the snow as visual clues of wind slab formation and avoid steep slopes, convex rolls, and cornices where you see these signs.

    (11/25/2020) Test slopes can give you a lot of good information about how new snow has set-up after or during a storm. This test slope shows that wind slabs are sensitive and propagating easily.

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1

    At lower elevations, 3-5" of dense snow sits above ~6" of lighter, lower density snow. All of this rests on top of a stout melt-freeze crust. By Tuesday afternoon snow levels are expected to rise to 5000' and slopes below treeline will be weighted down with a mix of wet heavy snow and possibly rain. This is a recipe for wet loose avalanches on all aspects. Pay attention to rising temperatures. Increasing roller balls and pinwheels are an indication the snow surface is weakening. Stick to terrain below 35 degrees if you experience rain or see rollerballs beginning to accumulate snow as they roll. With a firm crust below the surface, even a small wet avalanche may easily entrain more snow and have the power to knock you down. Use extra caution around terrain traps like cliffs and gullies.

     

    (12/13/2020) Roller balls are an early sign of wet snow. If these roller balls had grown any larger we would have chosen lower angle terrain to avoid triggering a loose wet avalanche.

Avalanche Discussion

Soft, cold, fluffy snow fell Friday onto a firm melt-freeze crust. More snow followed Sunday, but little avalanche activity was reported.

At middle and upper elevations, 10-15 inches of soft and weak snow is reasonably well bonded to the melt-freeze crust below. When new snow, strong winds, and rising temps arrive Tuesday the weak snow may fail and the crust will provide a good sliding surface for avalanches. This is a set up for dangerous avalanche conditions.

Currently, at lower elevations, the snowpack is "upside-down" and several inches of heavier snow sits on top of ~6-8 inches of weaker, lighter snow. This is above the firm crust and as more snow, and possibly rainfall, wet loose avalanches will be possible.

Regions covered