Bollettino valanghe

Northwest Inland

Dec 16 – 17, 2012Avalanche Canada
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Archiviato · scaduto 14 years ago

Pericolo valanghe

Tue
Wed
Alta quota
3 · Marcato
Limite del bosco
2 · Moderato
Sotto il limite
2 · Moderato
Apri la mappa completa

In sintesi

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–4
    Storm slabs might be encountered on steeper slopes with recent new snow. The bigger issue is linked to the wind. Be alert for new and buried wind slabs behind ridges and ribs.

  • Deep Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    2–6
    A deeply buried facet/crust weakness exists. Very large and destructive avalanches may be triggered from thin snowpack areas or by heavy loads such as a storm slab stepping down, or a snowmobile spinning its tracks.

Confidence

Fair - Due to limited field observations for the entire period

Weather Forecast

On Monday & Tuesday the region will see a cool unstable onshore flow with light SW winds, light snowfall with no significant accumulation, and freezing level near valley bottom. The next system is not arriving until sometime Wednesday when a Gulf of Alaska Low starts sliding south off the coast.

Avalanche Summary

On Wednesday last week, a snowmobile triggered a hard wind slab at the Sinclair snowmobiling area. It failed on the November crust/facet layer 30 cm above the ground while side hilling. This deep crust/facet layer has been the failure plane for a number of large avalanches further to the west and was suspected to have failed at the Hankin-Evelyn area last weekend.

Snowpack Summary

Storm snow instabilities are likely slowly settling and gaining strength. Spotty surface hoar was buried in the upper snowpack, particularly in sheltered treeline areas. New and buried wind slabs are widespread and exist on a variety of alpine and exposed treeline slopes due to variable winds. Of key concern is a November facet/crust layer which can be found near the base of the snowpack. This layer, which is widespread, can be triggered from thin-spot trigger points, or with a heavy load, such as storm slabs stepping down, a cornice fall or a snowmobile track digging a trench. It has the potential for large, destructive avalanches. . In general the snowpack depths, and therefore strength is highly variable due to windy conditions this season.

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