Avalanche forecast

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Wallowa Avalanche Center
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Avalanche danger

Alpine
3 · Considerable
Treeline
3 · Considerable
Below
3 · Considerable
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Highlights

Continued wind and new snow will add to the size of the wind slabs that have been forming throughout this storm.  You will find these slabs of wind-deposited snow on west through east-facing slopes near and above treeline. Large accumulations of new snow below have created storm slabs. Choosing slopes lees than 30 degrees is recommended today to avoid avalanches.

Dangerous avalanche conditions exist. Careful snowpack evaluation, cautious route-finding, and conservative decision-making are essential.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–3

    The ongoing storm will bring more snow and loading winds today. This will increase the size of the wind slabs that have been growing since Friday. Avoid slopes >30 degrees that have been loaded by the wind. Cornices, dune-like formations, textured snow, smooth lense-like drifts, or shooting cracks are all signs of wind slabs.

    Blowing snow accumulates much faster than snow falling from the sky.  This can create avalanches that will break much deeper than the amount of snow that has fallen in wind-protected areas. Fluctuating temperatures, rain, and new snow have created a varied upper snowpack. There are many layers that could become the sliding surface for a new wind slab avalanche. 

    (3/31/2023)

    Shooting cracks are a sign of wind slabs.

  • Storm Slabs

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

     Consistent snowfall since Friday afternoon has created storm slabs. These slabs will continue to grow in size today.  These slabs sit upon crusts and varying densities of snow. As more snow is added the likelihood of triggering a storm slab avalanche increases. If you find dense snow sitting on a crust or lower-density snow, move to lower-angle terrain (< 30 degrees).

    Two natural storm slabs were reported yesterday in the Southern Wallowas. Recent new avalanches are a red flag of instability.

    (4/1/2023)

    Noticed this R1 D1.5 natural avalanche while ski touring in the Western Wallowas today (Saturday). This soft slab avalanche consisted of the newest snow that fell the morning of April 1st. I think a large chunk of snow may have dropped from an overhanging tree limb onto the the steep, west facing slope below, triggering the small slide. This was an obvious redflag telling us the new snow in this location was unstable. The elevation of this west facing slope  was about 6400' .

    SS-N-U-R1-D1.5-S

     

    Photo: TG

Avalanche Discussion

A brief break in snowfall overnight gave the snowpack a moment to adjust to all the new snow.  The short break is not enough time for things to settle out and become safe. Winds continued to blow and redistribute snow. More snow and wind today will keep the avalanche hazard at Considerable. Treat all slopes > 30 degrees as suspect, if you have any doubt about the stability of the snow, move to slopes  < 30 degrees.

Consistent snowfall and temperature variations have created a varied upper snowpack. Most slopes besides north-facing terrain have layers of new snow with melt-freeze crusts sandwiching them,  In between these crusts, the density of snow varies. In some places, the snow between the crusts is still soft and low-density. These "crust sandwiches" can create avalanches. Reports of whumpfing and propagation in Extended Column Tests continue to come in from the Western Wallowas. The layer responsible for these collapses is a crust sandwich. This reactive combination has been found between 7100' and 8300' on Northwest, East, and South aspects. If you experience whumpfing, dig down to investigate what caused the collapse in the snowpack. Whumpfing is a red flag of instability, if you experience whumpfing it is advised to avoid slopes steeper than 30 degrees on similar aspects and elevations to where the whumpf occurred. You can watch a video from forecaster Victor McNeil showing this problem here.

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