Avalanche forecast

Northern Wallowas

Wallowa Avalanche Center
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Avalanche danger

Alpine
4 · High
Treeline
4 · High
Below
3 · Considerable
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Highlights

Moderate to strong wind and heavy snowfall has created very dangerous avalanche conditions.  Near and above treeline destructive wind slabs exist. Below treeline, you will find large storm slabs. You can avoid these avalanche problems by choosing slopes < 30 degrees that are not near adjacent avalanche paths.

Avalanche problems

  • Wind Slabs

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

    Almost 2" of water for 24" + of new snow has fallen since Friday (3/31) afternoon. Winds at the Kip Rand weather station at 7434' have been SW 20-30 mph with gusts to 45 mph for the past 24 hrs. The combination of new snow and wind builds large wind slabs. Traveling in avalanche terrain near and above the treeline is not recommended.

    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 High near and above treeline and Considerable below. Treat all slopes > 30 degrees as suspect, if you have any doubt about the stability of the snow, move to slopes < 30 degrees. Avoid recreating in terrain connected to or in the run-out zone of avalanche paths.

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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