Avalanche forecast

Elkhorns

Wallowa Avalanche Center
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Avalanche danger

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Out of date — this forecast expired 3 years ago.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

Highlights

Moderate westerly winds the last several days have easily transported significant amounts of light density new snow onto leeward terrain features and built reactive wind slabs 1-2' deep on N-E-S aspects near ridgeline and cross-load ribs and gullies mid-slope. Avoid slopes >30 degrees with recent wind deposit and watch for loose dry avalanches on slopes >35 degrees. 

Today's forecast is sponsored by Wallowa County Gamblers Snowmobile Club

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Avalanche problems

  • Wind Slabs

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

    Between 12-18" of new snow has fallen on the Elkhorns since last Sunday, 2/26.  The new snow is very light density and has been easily transported by moderate SW winds yesterday and more westerly winds overnight. Overnight the winds shifted from the SW to the WNW and are currently in the teens gusting 20's on Mt. Howard (8000'). Riders are likely to find 1-2' reactive wind slabs on steep (>35 degree) on N-E-S aspects near ridgeline and on cross-loaded terrain features mid-slope. Look for smooth rounded pillows below ridgeline and on the leeward side of ribs and gully features mid-slope. It is best for the next few days to avoid steep alpine terrain where reactive wind slabs may lurk.

    Check out my observation report from Anthony Lakes on Wednesday.

  • Loose Dry

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1

    The 12-18" of light density snow that has fallen since 2/26 is not bonding well to slick melt-freeze crusts or wind-hardened surfaces on steep (>35 degrees) slopes. While these slides may be small, they could pick up speed rapidly and take you for a ride into trees, rocks, and over cliffs. Avoid slopes >35 degrees where the new snow is not bonding well to the underlying old snow surface.

Avalanche Discussion

Protected and Sheltered Slopes Below Treeline

The snow quality on more protected and sheltered terrain is incredible right now. The cold temperatures and constant scud storms have left up to 18" of lovely light density snow in the Elkhorn Mountains. This is the place to find the best snow quality and stability. There really isn't a good reason to go above treeline - unless you like to punish yourself with variable and more unstable conditions.

Wind Slabs

While great conditions are to be had below treeline, the situation changes dramatically as you move to treeline and above. If you are moving above treeline, then a new terrain mindset is warranted. It will be challenging to negotiate and avoid the wind slab hazard at upper elevations. The winds have been variable the last 36 hours and have moved the light density snow around considerably. You could easily find pockets of wind slab on the southside of gully and rib features as on the northside. The uncertainty of where pockets of wind slab exist will be high for the next several days. Attempting to "thread the needle" is not a good way to move through the mountains and stay safe. Again, the best snow quality will be found below treeline.

Persistent Slabs

Over the last few weeks the buried persistent weak layers in the upper and lower snowpack have been mostly unreactive to human-triggering and have been gaining strength. I want to stress that pesistent grain types still exist throughout our snowpack. In particular, we have several facet/crust combos in the upper snowpack (top 3 feet) that remain a concern. There are also still some pockets of preserved and buried surface hoar. As our favorite astrologist Carl Sagan said, "The absence of evidence is not evidence of absence." The load from the new storm snow may be enough to reactivate these more deeply buried weak layers. Be sure to evaluate the snowpack on any slope >30 degrees for buried persistent weak layers. If you see poor structure in the upper snowpack - namely strong over weak - then be sure to test those suspect layers for reactivity. Also, it is good protocol to avoid possible trigger points in the terrain like convex rollovers, unsupported slopes above and below cliff bands, slopes punctuated with rocks, and areas in the terrain where the snowpack is shallow, <4' deep.

Storm Slabs

The reason storm slabs are not listed as a problem type is the new snow is super light in density and just doesn't seem to have the cohesion yet to propogate fractures over large distances. This will change in the coming days as the new snow consolidates and becomes more dense. We are likely to see increased reactivity at the old/new interface as the storm snow stiffens into a slab. Currently, there will be areas where the wind has transported the new snow and created denser pockets that may display slablike properties. There are also pockets of buried surface hoar that got covered by the storm snow starting on 2/26. It will be difficult to assess the instability of a slope without digging down a couple of feet and looking for persistent grain types/layers. Do your homework before jumping out on any slope >30 degrees.

Loose Dry Avalances

We have 12-18" of super light snow that is not bonding well to any slope that has an old melt-freeze crust or wind scab. In particular, it will be good to avoid steep (>35 degree) terrain where triggering a point release or sluff may get that new snow moving quickly down the slope, taking you off your feet or sled, and pushing you into terrain traps or stationary obstacles.

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