Avalanche forecast

Northwest Coastal

Jan 18 – 19, 2014Avalanche Canada
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Avalanche danger

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

Avalanche problems

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible - Likely
    Size
    1–4
    New snow and wind will likely set up reactive slabs, especially in lee and cross-loaded terrain in the alpine. Given the recent history of large avalanches, there is a chance that a small avalanche triggered near the surface could step down.

  • Deep Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    4–7
    A weak layer of facets/depth hoar at the base of the snowpack has been responsible for some recent very large avalanches. The likelihood of triggering this layer is now considerably reduced, but the consequences associated with this layer are huge.

Confidence

Fair

Weather Forecast

A strong upper ridge of high pressure will dominate the weather pattern for a week or more. However, a weakening Pacific front will move through the ridge Saturday and give light to moderate precipitation through Saturday evening.Saturday Night: Freezing Level: 1100m; Precip: 2/12mm 4/15cm Wind: Strong, SWSunday: Freezing Level: 800m; Precip: Nil; Wind: Light, West.Monday: Freezing Level: Rising throughout the day to 2000m. Precip: Trace; Wind: Mod, South.Tuesday: Freezing Level: 2500m; Precip: Nil; Wind: Mod, SW.

Avalanche Summary

Isolated naturals to size 1.5 were reported from steep solar aspects Friday afternoon. Explosives are still producing results in the alpine if the technician finds just the right spot. On January 13/14 there was a widespread avalanche cycle involving all aspects/elevations. Multiple natural releases up to size 4.0. Most of these avalanches would have run on the early January surface hoar layer buried under the storm snow at treeline and below treeline in all the region and some on the deep persistent basal facet layer in the alpine in the Northern part of the region.

Snowpack Summary

In the North, the early January surface hoar buried at around 1 m deep at treeline and below treeline is showing to be a main concern since it proved to be very active during the last storm even on low angled terrain. The basal facets also became reactive in the last rapid loading. These are found in the alpine and at treeline under over 2 m of snow in some areas. The persistent weak layers mentioned above are also found in the Southern part of the region, but are not showing as much reactivity. The extensive wind slab formation that happened during the SW wind event have most likely started to bond to the underlying surface in the alpine and at treeline. However, expect steep crossloaded or steep lee features to weaken during the day especially if the sun hits those slopes.

Regions covered