Avalanche forecast

Northwest Inland

Feb 6 – 7, 2016Avalanche Canada
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Avalanche danger

Mon
Tue
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
2 · Moderate
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Highlights

In the far western side of the region more snow is expected to fall. In these areas, the Avalanche Danger may be HIGH on Sunday.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely - Very Likely
    Size
    1–3
    Moderate amounts of new snow and extreme winds will promote ongoing wind slab activity at treeline and in the alpine. Hard wind slabs may propagate over surprisingly wide distances.

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–4
    New snow has been slowly accumulating over a layer of facets and surface hoar, and in many places the overlying slab may now be primed for human triggering.

Avalanche Summary

In recent days wind and snow promoted natural slab avalanche activity to size 2 in the Howson Range. Continued snow and wind on Sunday will promote ongoing wind slab activity with the potential to step down to deeper, more destructive persistent weak layers.

Confidence

Moderate - Due to the number of field observations

Weather Forecast

On Sunday and Monday another windy storm will impact the region. Expect between 5-15mm of precipitation per 24 hour period with freezing levels climbing from 500m on Sunday morning to 1800m by Monday afternoon. On Tuesday, expect a mix of sun and cloud with the freezing level shooting up to 2500m. Ridgetop winds should remain strong to extreme from the southwest for the forecast period.

Snowpack Summary

New snow and wind forecast for Sunday will create reactive new wind slabs throughout the day adding to an ongoing wind slab problem. New snow accumulations will also add mass and reactivity to a developing slab which overlies recently buried surface hoar. This layer was observed in the Hankin area and may exist in many other places. The early or mid January surface hoar layer is generally 30-50 cm deep, although it may be buried by up to 100cm of snow in the far west of the region. Observers have found this persistent weakness on all aspects and at all elevations. It consistently produces moderate "pops" results in snowpack tests. Below this, the Boxing Day surface hoar problem may also be lurking. The mid and lower snowpack is generally quite weak and faceted, especially in lower snowpack areas such as the Babines.

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