Boletín de aludes

Purcells

Feb 27, 2019Avalanche Canada
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Archivado · caducó 8 years ago

Peligro de aludes

Thu
Fri
Alta montaña
2 · Moderado
Límite del bosque
2 · Moderado
Bajo el límite
2 · Moderado
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Lo esencial

Fresh wind slabs are sitting on top of buried wind slabs that are sitting on facets (weak, sugary snow). The fresh wind slabs are touchy and the buried wind slabs may remain reactive to human triggers longer than is typical.

Problemas de aludes

  • Wind Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Possible - Likely
    Tamaño
    1–2
    Fresh wind slabs are sitting on top of buried wind slabs that are sitting on facets (weak, sugary snow). The fresh wind slabs are touchy and the buried wind slabs may remain reactive to human triggers longer than is typical.

  • Persistent Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Unlikely - Possible
    Tamaño
    1.5–2.5
    Two weak layers of surface hoar are buried between 30 and 70 cm down in the snowpack. These layers are most pronounced at treeline and below treeline elevations and remain possible to human trigger.

Confidence

High - The weather pattern is stable

Weather Forecast

TUESDAY NIGHT: Clear / Light, easterly winds / Alpine low -14.WEDNESDAY: Sunny / Light, easterly winds / Alpine high -6.THURSDAY: Mix of sun and cloud / Light, southwesterly winds / Alpine high -9.FRIDAY: Mostly cloudy / Light, southwesterly winds / Alpine high -10.

Avalanche Summary

On Saturday there was a report of a skier triggered size 2 persistent slab avalanche 30-50 cm deep on a northeast aspect in the Dogtooth range. This person was seriously injured after being swept over a 30 m cliff and carried by the avalanche for a total of 650 m. On Wednesday there was a report of a human triggered size 2 persistent slab avalanche in the Gorman Lake area. There is a great MIN report detailing this avalanche here.During the past week there have been numerous reports of persistent slab avalanches. These avalanches are becoming fewer and further between, but they are still being triggered by people and are large enough to have a high consequence.

Snowpack Summary

Strong northeasterly ridge-top winds on Monday created fresh wind slabs on lee features at treeline and above. Additionally, there are buried wind slabs on a variety of aspects that are sitting on facets (sugary snow) which may cause them to remain reactive to human triggers longer than what is typical for a wind slab problem.Lower down there are two layers of surface hoar (weak, feathery crystals) that were buried at the end of January and mid-January. These layers are around 30 to 80 cm deep and are most prominent at treeline and below. The surface hoar may sit on a crust on south facing slopes in specific locations which is a dangerous combination.The base of the snowpack is composed of weak and sugary faceted grains that sit on a crust. This weak layer has produced large and destructive avalanches that are sporadic in nature and very difficult to predict. See the Forecaster Blog here for more information on this problem.

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