Bollettino valanghe

Northwest Coastal

Dec 14 – 15, 2011Avalanche Canada
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Archiviato · scaduto 15 years ago

Pericolo valanghe

Fri
Sat
Alta quota
3 · Marcato
Limite del bosco
3 · Marcato
Sotto il limite
3 · Marcato
Apri la mappa completa

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Very Likely
    Dimensione
    1–4
    Expect new wind slabs on north through east aspects. Loading may occur lower on the slopes due to forecast high winds in some parts of the region. There's a lot of snow available for transport.

  • Storm Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Very Likely
    Dimensione
    1–4
    Storm slabs will continue to form with forecast snow. Pay attention to the snowfall amounts in your local area, they may vary through the region. More snow = thicker slabs. They can run far, fast and be destructive.

Confidence

Good - -1

Weather Forecast

Thursday: Mainly dry cold conditions during the day. Strong ridgetop winds from the southwest. Freezing levels remain at valley bottom. Light snow beginning later in the afternoon. Friday: Snowfall amounts accumulating up to 30cm. Winds remain strong from the south west. Freezing levels could spike to 1700m in the southern part of the region only (Stewart and south). Saturday: Expect freezing levels to drop back to valley bottom. Snow continued through the weekend.

Avalanche Summary

Several operations got out Tuesday to do some helicopter bombing. They reported numerous avalanches up to size 3 on east-southwest facing slopes. On Wednesday widespread natural avalanches up to size 2 were reported. These avalanches all ran on the December 09/12 (111209, 111212) buried surfaces ( surface hoar, melt-freeze crusts). With more wind, snow and rising freezing levels Friday/Saturday we can expect another natural avalanche cycle.

Snowpack Summary

The southern part of the region has received up to 50cm of new snow (Kasiks, Terrace areas) and less snowfall to the north. This is forming storm slabs at all elevations. This new snow is being blown around by strong southwest winds creating new wind slabs on lee slopes. Buried beneath the new snow sits a variety of weak snow surfaces (surface hoar, melt-freeze crusts, and facetted snow). This crust is up to 20cm in thickness and extends up to alpine elevations in the south, and around 1000m in the north. The surface hoar growing on the crust was sized up to 10mm. A strong temperature gradient in the top 30cm was reported to be faceting snow below the surface crust. These layers have met their threshold and widespread avalanche activity has occurred. Here's hopes that this surface hoar will get cleaned out in most places. The crust may stick around and create a new sliding surface for Fridays snowfall. If freezing levels do rise to 1700m on Friday we may see rain and new crust formation Saturday when the temperatures drop back down the the valley.The mid and lower snowpack are well settled and strong.

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