Boletín de aludes

Olympics

Northwest Avalanche Center
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Peligro de aludes

Sat
Alta montaña
3 · Notable
Límite del bosque
2 · Moderado
Bajo el límite
1 · Débil
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Desactualizado: este boletín caducó 3 years ago. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

You can trigger a large slab within wind-drifted snow near ridgeline and at upper elevations, particularly on atypical aspects. Winds stripped snow down to a crust on some sides of ridgelines, so expect large reactive pillows on the opposite side. Steer around wind-loaded features 35 degrees and steeper.

Problemas de aludes

  • Wind Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Possible
    Tamaño
    1–2

    As of Thursday NPS Rangers found northerly winds had loaded atypical S and SW aspects with cracking snow in large pillow-like drifts within the otherwise low-density snow. Slabs were 1-1.5 ft deep, sitting above lower density less wind-affected snow. As winds continue to load atypical aspects Thursday night, expect slabs to be large (1-2 ft deep) on Friday. Slab activity could be widespread at upper elevations, with reactivity limited to heavily loaded drifts in the lee of ridgelines at middle elevations. Look for the typical signs of wind-drifted snow: Firm or punchy layers, lens-shaped pillows, textured snow surfaces, fresh sharp cornices, and active snow deposition onto a slope. If you encounter any of these, steer around the wind-loaded slope in question if it is steeper than 35 degrees or the slope rolls out of sight below you. 

    (1/11/2024)

    Wind-textured snow and pillows where you might trigger an avalanche on a steep or unsupported slope on Friday.

    Photo: Olympic NPS Rangers

Avalanche Discussion

While Hurricane Ridge still lags historical mid-January snow depths, we're catching up quickly in the last week! The first of two storms brought 8" of snow by last Saturday morning. A storm cycle Monday-Wednesday added around 22" to the total snow depth at the Ridge. A test pit in the gallery shows a layer of firmer snow above lower density snow. Below that, you might find a breakable crust formed during mild temperatures on 1/8. Slab reactivity should be limited to the snow above the 1/8 crust. Temperatures have been cold, likely helping preserve cold, dry snow on all aspects. In many cases, this recent snow lies on bare ground.

With all the recent low-density snow, you may be able to trigger a dry loose avalanche in less wind-affected terrain. Dry loose avalanches can run far and fast in very steep terrain approaching 40 degrees.  Additionally, cold sunshine on Friday may still have enough energy to destabilize the low-density snow surface, creating small loose avalanches. Keep these in mind and reduce your exposure to very steep or cliffy terrain if you start to see rollerballs.

There's some uncertainty given the potential for a minor upslope snowfall event Wednesday night at Hurricane Ridge. Most models don't indicate more than an inch or two of snow. But with the very cold temperatures in place, it won't take much moisture This could add more low-elevation snow than forecast or create a low-density storm slab on all aspects. If you see something that doesn't line up with the forecast, choose simpler terrain and slopes less than 35 degrees to reduce your risk.

While it now looks like winter, rocks, bushes, holes, creeks, and logs could lurk just under the surface. A photo in the gallery shows bare ground covering south-facing terrain up to 5000 ft just 7-8 days ago.

NWAC may issue a gray "No Rating" for an elevation band when there is not enough snow to present an avalanche hazard.

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