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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Highlights

Triggering an avalanche in wind drifted snow will be likely Tuesday despite the transition to clear and sunny weather. A weak layer of snow exists between the recently wind transported snow and the old firm surface. Identify where wind deposited recent snow and stay away from lee slopes steeper than 35 degrees where you see evidence of wind affected snow such as cornice development and pillow-like drifts.

Avalanche problems

  • Wind Slabs

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

    Very strong winds built shallow but reactive wind slabs Monday. Meadows Pro Patrol reported easily triggering widely propagating wind slabs without the use of explosives. Wind slabs triggered Monday morning were generally in the 4-6" range, but wind transport continued through the day. Wind slabs which you could trigger Tuesday will be thicker, but still widely propagating. Wind transport was intense, however, snow accumulation was modest at lower elevations, so expect larger potential avalanches as you ascend. The onset of precipitation Monday morning coincided with plummeting temperatures and, as a result, Monday's snowfall is poorly bonded to the melt-freeze crust from the weekend's nice weather. A layer of low-density snow lies between the weekend's crust and still enlarging wind slabs. In wind-sheltered areas below treeline, a layer of surface hoar has been preserved and in other areas, the reactive layer is simply low-density snow beneath a wind slab. Regardless of the culprit, a layer of reactive snow is buried between Monday's wind affected snow and the firm surfaces from the weekend. Take note of recent cornice development, give them wide berth and steer around slopes directly below cornices where snow deposits are likely. Identify and avoid wind loaded slopes where you see firm and textured snow surfaces, cracking or whumphing in the snow as you travel, and pillow-like features.

    As always, use blowing snow and cornice formation as visual clues where slabs may be forming. Hollow sounding and firm or textured snow are other clues that wind transport is building slabs. The winds have been strong enough that slabs have developed further downslope than normal so be alert for cross-loaded terrain features and midslope slab formation. Winds are forecast to shift direction and freshly drifting snow will cover some of our most obvious clues to wind slab formation. Choose terrain conservatively through this transitional weather period and choose conservative routes away from start zones and steep lee slopes when in doubt.

     

    Blowing snow, firm and textured snow, and cornice formation are all evidence that wind slabs are likely to be forming on lee slopes.

Avalanche Discussion

Tuesday will be a transition day between stormy weather and high pressure. Despite the tempting weather forecast, conservative decision making is essential. Give freshly formed wind slabs a chance to heal. Identify and avoid slopes over 35 degrees where wind deposited snow has accumulated. Winds were very strong Monday and formed wind slabs at all elevations, and a weak layer of snow exists between the firm snow surfaces from the weekend and Monday's snowfall. 

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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