Bollettino valanghe

Northwest Inland

Feb 1 – 2, 2015Avalanche Canada
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Archiviato · scaduto 12 years ago

Pericolo valanghe

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

In sintesi

As snow accumulates on Monday, the Avalanche Danger will rise. Expect reactive new storm slabs to form.

Problemi valanghivi

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Unlikely - Possible
    Dimensione
    2–5
    In the mid snowpack there are a few crusts which may be reactive with the potential for large avalanches. Although less likely to trigger, these persistent weak layers may "wake-up" in response to a large trigger such as a cornice fall.

  • Storm Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    1–3
    New snow and wind on Sunday night and Monday will form new storm slabs. Watch for triggering in higher elevation, wind-exposed terrain.

  • Deep Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Unlikely - Possible
    Dimensione
    3–6
    Although less likely to trigger, recent avalanche activity suggests weak layers buried at the beginning of the winter should still be our radar, especially in the north of the region. Avalanches at this interface may reach their run-out zones.

Confidence

Fair - Due to the number of field observations

Weather Forecast

Another pacific frontal system will bring snowfall to the coast on Monday. Lingering flurries are expected on Tuesday before a weak dry ridge of high pressure builds on Wednesday.    Sunday night and Monday: Up to 15cm of snow / Strong southwest winds / Freezing level at valley bottom    Tuesday: Very light snowfall and broken cloud / Moderate southwest winds / Freezing level at valley bottom    Wednesday: Broken cloud / Moderate southwest winds / Freezing level at valley bottom

Avalanche Summary

Several storm slabs to size 2.5 were reported in the wake of Thursday night's storm. With more snow and wind on the way on Sunday night and Monday, I'd expect continued storm slab activity. It's important to keep in mind, a surface avalanche in motion may be what it takes to trigger deeper, more destructive persistent slab avalanches.

Snowpack Summary

Prior to the weekend, moderate to locally heavy snowfall and strong southwest winds built deep storm slabs which may still be reactive in wind-exposed terrain. More snow and wind forecast for Sunday night and Monday will add to this ongoing storm slab problem.About 70cm below the surface, you'll likely find a rain crust which was buried on January 26. Limited observations suggest the overlying slab may have a reasonable bond at this interface.A rain crust and/or surface hoar layer buried mid-January may be found at variable depths (in some areas over 100cm below the surface). This layer has reportedly gained significant strength, although I would keep it on my radar especially at higher elevations or in the far north of the region. Near the base of the snowpack is a crust-facet combination buried in November. This deep persistent weakness was recently reactive, and may still be touchy in the far north of the region. Wherever you are, I'd be cautious of this deep and destructive layer. Possible triggers include thin spot triggering in high elevation terrain, or a cornice fall.

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