Boletín de aludes

Mt Hood

Northwest Avalanche Center
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Peligro de aludes

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

Lo esencial

Heavy snowfall along with increasing winds and temperatures will create dangerous slabs you can trigger at any elevation. Avalanches could be large on wind-loaded slopes or in areas where weak snow surfaces have been preserved. Avoid open slopes steeper than 35 degrees.

Problemas de aludes

  • Wind Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Likely
    Tamaño
    2

    We're expecting 12-18" of low-density snowfall with moderate winds shifting from the SE to the WSW during the storm and loading a variety of aspects. Soft slabs 2-3 ft deep may look inviting in wind-loaded areas, but you shouldn't fall for the bait on a steep, open slope. These slightly firmer slabs of snow overly lower density snow above a crust. Slabs could easily injure you or worse. Natural avalanches are possible in heavily wind-loaded terrain features, so limit your exposure to steep slopes above you. Avoid all wind-loaded slopes steeper than 35 degrees. Seek safer travel options along ridgelines and wind-scoured slopes.

     

    Example: Cornices suggest wind loading on the slopes below. Check your slope angle. If it's over 35 degrees, you could trigger a large avalanche on a similar slope on Thursday.

    Photo: Joe Dellaporta

  • Storm Slabs

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

    High snowfall rates through Thursday will lead to storm instabilities. Gradually warming temperatures early Thursday give the storm snow a poor stability structure. The storm snow needs time to stabilize and it won't have the chance as snow continues to stack up on Thursday. Slabs could be large if they involve a weak snow interface (see discussion), and will slide rapidly on firm bed surfaces. Avoid all open slopes steeper than 35 degrees with 8" or more of snow overlying the 02/14 interface.  Propagating cracks on kick turns, hand pits, and simple slope tests should all be used to confirm the problem. However, in some areas, snow may fail as dry loose avalanches which could rake you into a band of trees or over a cliff.

    Example: Storm slabs like this may be easily triggered on Thursday at lower elevations. 

    Photo: Andrew Kiefer

Avalanche Discussion

When the avalanche problems are large and difficult to manage, keep your terrain selection simple and enjoy the lower-angle powder.

4" of cold, low-density snow came in with very little wind on Wednesday afternoon. Good news first: This created some rapidly improving conditions. The bad news? Some pockets of surface hoar may have been buried on the northern half of the compass at lower and middle elevations and we have uncertainties regarding the potential distribution. These weak snow grains are worth thinking about if you travel onto north-facing slopes where a slab releasing on a 30-degree slope is not out of the question. This adds to our list of potential weak interfaces: Weak snow has also been found near the 2/11 interface and above the early February crust, but the potential reactivity on these interfaces is expected to be isolated and primarily at upper elevations.

You're likely to find a crust on the south half of the compass below 7000 ft due to sunshine on Tuesday. Strong WSW winds last weekend created old, large slabs earlier in the week. A collapse reported Tuesday at 10,000 ft on the E side of the Hogsback was a sign that some older weaker snow layers had not healed. There was also a small skier-triggered avalanche at 6200 ft on an E aspect on Tuesday (see photo in the gallery).

The lower elevation snowpack has endured a beating after last week's warm-up but expect rapidly increasing danger on steeper open slopes. Below 5000 ft shallowly buried obstacles remain hazards and open creeks are difficult to cross in some areas.

Your avalanche, snowpack, or weather observations are extremely valuable to the forecasters at NWAC. Help create a more accurate avalanche forecast by submitting your observations here. 

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