Boletín de aludes

Lizard-Flathead

Feb 24 – 25, 2021Avalanche Canada
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Archivado · caducó 6 years ago

Peligro de aludes

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

Don't let your guard down during clear skies; recently formed slabs and a buried weak layer can still be triggered by riders.

Problemas de aludes

  • Persistent Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Possible - Likely
    Tamaño
    1.5–3

    Many large avalanches have been triggered on this layer of surface hoar, faceted grains, and/or a melt-freeze crust, found around 50 to 80 cm deep. The layer has been most problematic around treeline elevations and in openings below treeline, but also reaches into the lower alpine. Avalanches have occurred on surprisingly shallow slope angles and the layer can easily be remotely triggered.

  • Storm Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Likely
    Tamaño
    1–2.5

    Both storm and wind slabs remain likely to be triggered by riders on Wednesday. The slabs may be around 20 to 50 cm thick, depending on how much snow fell in your riding area. Use particular caution on sun-exposed slopes as well as in lee terrain features near ridges. Conservative terrain travel is recommended until the snow has some time to bond to the snowpack.

Confidence

Moderate - Uncertainty is due to how quickly the snowpack will recover and gain strength.

Weather Forecast

TUESDAY NIGHT: Partly cloudy, 20 km/h north wind, alpine temperature -10 C.

WEDNESDAY: Clear skies, 30 km/h west wind, alpine temperature -9 C.

THURSDAY: Cloudy with snowfall, accumulation 10 to 20 cm, 30 km/h southwest wind, alpine temperature -9 C.

FRIDAY: Cloudy with snowfall, accumulation 5 to 10 cm, 30 km/h west wind, alpine temperature -9 C.

Avalanche Summary

Many large (size 2 to 2.5) storm and wind slab avalanches were triggered naturally, by skiers, and using explosives on Monday. Many of the releases occurred out of alpine terrain but a few occurred at and below treeline.

Looking towards Wednesday, natural avalanche activity is expected to diminish, except perhaps on steep southerly slopes from solar warming. Human triggering of storm, wind, and persistent slabs will remain possible.

Snowpack Summary

Around 20 to 50 cm of snow fell on Monday and Tuesday, with the most in the east of the region near the divide. The freezing level hovered around 1600 m for much of the storm, forming storm slabs above and soaking the snowpack below. The snow fell with strong southwest wind, forming wind slabs in exposed terrain at treeline and alpine elevations.

All the snow and rain has loaded a weak layer found around 50 to 80 cm deep, buried late-January. The layer may consist of weak and feathery surface hoar, sugary faceted grains, or faceted grains associated with a hard melt-freeze crust. Many avalanches in the past few weeks have been triggered on this layer.

There are presently no deeper concerns.

Terrain and Travel

  • Choose conservative terrain and watch for clues of instability.
  • Back off if you encounter whumpfing, hollow sounds, or shooting cracks.
  • The trees are not the safe-haven they normally are at this time. Terrain at treeline is primed for human triggered 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.

Regiones cubiertas