Boletín de aludes

Northwest Inland

Mar 4 – 5, 2021Avalanche Canada
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Archivado · caducó 6 years ago

Peligro de aludes

Sat
Sun
Alta montaña
3 · Notable
Límite del bosque
2 · Moderado
Bajo el límite
2 · Moderado
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Lo esencial

Reactive wind slabs may linger on northeast to east-facing slopes. Shooting cracks and hollow-sounding snow beneath your skis are indicators of this. 

The sun really packs a punch these days. If the sun pokes out, watch for failing cornices and weakening moist snow surfaces.

Problemas de aludes

  • Wind Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Possible - Likely
    Tamaño
    1.5–2.5

    Cranking south-southwest wind and new snow have formed fresh new wind slabs. Reactive storm slabs may be found in isolated wind-sheltered terrain. 

    Large, looming cornices exist along ridgelines. They may become weak and fail during periods of solar radiation and rising freezing levels. Keep your head up and watch for obvious signs of warming like natural avalanches, snowballing, moist and sticky snow surfaces. 

  • Loose Wet

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Likely
    Tamaño
    1.5–2.5

    The sun packs a punch this time of year. Periods of sunshine could trigger loose wet avalanches. Keep your head up and watch for obvious signs of warming like natural avalanches, snowballing, moist and sticky snow surfaces. Large, looming cornices exist along ridgelines. They may become weak and fail during periods of solar radiation and rising freezing levels. 

     

Confidence

Moderate - Uncertainty is due to the limited number of field observations. Uncertainty is due to the timing or intensity of solar radiation and its effect on the snowpack.

Weather Forecast

Wednesday Night: Snow amounts 5-10 cm and ridgetop wind moderate from the South. Alpine temperatures near -4 and freezing levels 700 m.

Thursday: Mix of sun and cloud with a trace of new snow. Ridgetop wind light with strong gusts from the southeast. Alpine temperatures -2 degrees and freezing levels 1100 m. 

Friday: Cloudy with sunny periods and isolated flurries. Ridgetop wind moderate from the South. Alpine temperatures near -6 and freezing levels 700 m. 

Saturday: Mix of sun and cloud with ridgetop wid light from the South. Alpine temperatures near -8 and freezing levels 800 m.

Avalanche Summary

No new avalanche reports for Wednesday.

On Sunday, a few natural wind slab avalanches were reported up to size 2 at treeline and in the alpine on northeast and northwest aspects. Wind slabs were also easily triggered on leeward slopes by the weight of a skier. Numerous loose wet avalanches were observed from steep terrain features. 

On Saturday, we received some fantastic MIN reports showing significant wind effect and wind loading at upper elevations. Natural avalanches were reported as well as a skier-triggered slab size 1.5. 

Thank you for the MIN reports!!

Reactive wind and storm slabs are the primary concerns for the forecast period. Loose-dry sluffing will likely be seen from steep terrain features. 

Snowpack Summary

Over the past few days, 30-40 cm of new snow fell by Wednesday. Fresh winds slabs may be reactive on leeward slopes at upper elevations, while touchy storm slabs may be found in isolated wind-sheltered locations. Solar aspects are sporting a thin sun crust and below treeline elevations are seeing a melt-freeze crust.

The recent snow brings 60 to 90 cm of snow on a variety of old snow surfaces consisting of hard wind-affected snow in exposed terrain and weak, faceted snow or possibly surface hoar crystals in sheltered terrain. At this point, it seems like the snow is bonding to previous surfaces with the given conditions. However; a lot of uncertainty surrounds this possible interface and if, or where these potential persistent weak layers exist. They may become a problem with a significant change in the conditions like a big warm-up or increase in snow load. Something to keep on your radar. 

Basal faceted snow remains part of the snowpack structure in much of the region. 

Terrain and Travel

  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • Watch for signs of instability like whumpfing, hollow sounds, shooting cracks or recent avalanches.
  • Minimize exposure to sun-exposed slopes when the solar radiation is strong.
  • Pay attention to cornices and give them a wide berth when traveling on or below ridges.

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