Avalanche forecast

Southern Wallowas

Wallowa Avalanche Center
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Avalanche danger

Fri
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Out of date — this forecast expired 6 years ago.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

New snow and wind loading will continue to test the strength of a weak and shallow snowpack in the Northern Wallowas.  The abundance of snow available for transport combined with wind will form a new round of windslabs in leeward terrain.  If triggered, any size windslab could create enough weight to "step down" into older, weaker sugar snow producing a larger, more destructive avalanche.  Observe wind loading patterns and choose terrain carefully, avoiding wind loaded start zones and mid slope features.  

Avalanche problems

  • Wind Slabs

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

    The recent storm that cleared on Monday night (1/4) brought up to a foot of new snow to favored areas of the Northern Wallowas.  SW winds accompanied the storm and developed wind slabs in the upper part of the snowpack that then became covered by the tail end of that storm.  I would expect to see this "older generation" of windslab to have relaxed since then, and become more stubborn, but not alltogether impossible to trigger.  New snow and forecasted increased winds today will produce fresh windslabs on W-N-NE aspects at treeline and above treeline.   Observers at Wing Ridge yesterday noticed a fresh avalanche along the ridgeline that seemed to have stepped down into older snow.   

    Avalanche in leeward wind loaded terrain that quite possible stepped down into older snow.

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2–3

    The weak snowpack structure in the Northern Wallowas will continue to be tested by ongoing wind loading.  Hardness profiles, snowpack tests, and recent avalanches are all pointing to the fact that it is possible to trigger an avalanche up to 3 feet deep into old November facets (sugar snow).  The weak snow is capped by about a 1 foot slab of 1 Finger hard cohesive snow.  The Solstice Rain Crust sits above this slab of snow in a wide variety of thickness and strength, but mostly found at a little over 2 feet (70cm) from the snow surface.  Persistent slabs are hard to forecast for, especially at this depth.  Give your terrain a healthy margin of space towards consequential slope features, and stay out from under runout zones.  This flavor of avalanche is prone to remote trigger.   If obvious red flags are present (recent avalanches, ongoing wind loading, shooting cracks, or "whumphing"), choose simple, lower angle terrain with no overhead hazard in which to recreate.  

Avalanche Discussion

Observers on Tuesday found weak snowpack structure, consistently alarming snowpack test results, and natural avalanches (see below) to confirm dangerous avalanche conditions.  Excellent riding was found on terrain with slope angles less than 30 degrees.   

Regions covered