Boletín de aludes

Mt Hood

Northwest Avalanche Center
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Peligro de aludes

Tue
Alta montaña
2 · Moderado
Límite del bosque
1 · Débil
Bajo el límite
1 · Débil
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Desactualizado: este boletín caducó 4 months ago. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

Sustained moderate winds will transport fresh snowfall into small drifts that you can trigger on Monday. Reactivity will focus more on upper elevation steep or poorly supported lee slopes. Check the bond with the underlying crust and skirt the edges of patchy drifts.

Problemas de aludes

  • Wind Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Possible
    Tamaño
    1–1.5

    We're expecting 0.2-0.4" of water equivalent over the next 24 hours. This likely translates into 2-4" of colder snow above 7000 ft, with up to 2" of moist, sticky snow likely from 5000-7000 ft. Expect a strong increase in hazard as you ascend in the terrain, and even within the upper elevation band. Colder, drier snow at the highest elevations will be more extensively redistributed by persistent moderate ridgeline winds. In most areas slabs will build over a refreezing surface crust, but if you find the snow not as well bonded, slabs could be easier to trigger and propagate further across a slope. Most slab will be shallow, pockety, and focused on the down-wind side of ridgelines, underneath sharper corniced features. In upper elevation terrain, some drifted pockets may extend onto mid-slope features. Expect significant variations in hazard across the mountain and wherever you find more fresh snow and active wind transport.

    At middle elevations, the danger should remain isolated. Ribbons of redistributed snow and isolated drifts 6" or deeper should be easy to steer around. Even a small avalanche can push you into unfriendly terrain that may lack snow coverage. 

    Example: Keep on the lookout for cracking with uptrack tests within wind-drifted pockets.

    Photo: Joe Dellaporta

Avalanche Discussion

A mix of rain and snow continues to trickle into Mt Hood as the recent storms feel distinctly spring-like. Snow showers activity over the weekend brought 2-3" snow to upper elevation terrain around Mt Hood Meadows and around Cooper Spur. With intermittent snow showers and sun breaks, this snow quickly became moist and sticky, and was on the verge of becoming a concern for very shallow wet avalanches. This new snow sits above isothermal melt forms on a pit at 6800 ft on Cooper Spur. A similar well-settled, late-spring-like snowpack structure is likely to exist in most terrain below 7000 ft on the mountain. Wet snow surfaces existed on most lower and middle elevations on the mountain.  Slightly more new snow might be expected at upper elevations on the western slopes of Mt Hood where precipitation was more sustained, but generally light. This divergence in snow and precipitation totals from east to west across the mountain is likely to continue in the coming days.

Although the wind slab risk had yet to materialize on Sunday, we expect further cooling Sunday night to combine with a significant uptick in wind speeds to create more winter-like conditions than we have seen in the past 1.5 weeks. 

Since April 3rd, freezing levels have been flirting with the summit of Mt. Hood at nearly 10-11,000 ft and the snowpack has lost 15" of depth at Mt Hood Meadows Base. Snow depths above the more 3/31 crust have now consolidated into the 3-6" range on most slopes with snow coverage, but the fresh snowfall started adding back to that at higher elevations. The loss of snow coverage in recent weeks is dramatic in the images and should be on your mind as you ride terrain that typically might have better coverage this time of year. Open creeks, shallowly covered or exposed rocks, and snow moats opening up are all spring challenges that may be a month or more ahead of schedule this season.

As ski area operations gradually wind down, your observations are especially valuable to us.  Let us know what you see by submitting an observation here or on the AvyApp.

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