Avalanche forecast

Northwest Coastal

Jan 26 – 27, 2015Avalanche Canada
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Avalanche danger

Wed
Thu
Alpine
4 · High
Treeline
3 · Considerable
Below
3 · Considerable
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Highlights

Continued wind, snow and warming will add more stress to buried weak crystals. Very large avalanches have been running from the alpine to valley bottom. Conservative terrain selection remains critical.

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible - Likely
    Size
    3–7
    Storm loading and warm temperatures have added reactivity and destructive potential to weak crystals which formed in early January. With more snow on the way, very large avalanches remain a concern with potential to run all the way to valley bottom

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely - Very Likely
    Size
    1–4
    Continued heavy loading from snow and wind will create potent new storm slabs. Watch for increased reactivity in higher, wind-exposed terrain. At lower elevations where rain has fallen, destructive wet slabs are also possible.

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–3
    The snowpack is saturated at elevations where rain has fallen. If warm temperatures persist, pushy loose wet avalanches will remain a concern in steep terrain. Destructive wet slab avalanches are also possible where the snowpack is rain-soaked.

Confidence

Fair - Track of incoming weather systems is uncertain on Monday

Weather Forecast

An active moisture stream will continue to bring moderate snowfall with locally heavy accumulations in the south of the region. Monday night: Up to 30cm of new snow / Extreme southwest winds / Freezing level at 1200m Tuesday: Moderate snowfall in the morning easing by mid-day / Strong southwest winds / Freezing levels at 800m Wednesday: Light snowfall with up to 15cm falling that evening / Strong southwest winds / Freezing level at 800m Thursday: About 10cm of new snow / Extreme southwest winds / Freezing level at 1200m

Avalanche Summary

In recent days, a widespread natural avalanche cycle took place to size 3.5. These avalanches were triggered by loading from heavy precipitation, wind, and warm temperatures. Many avalanches failed within the recent storm snow, although numerous avalanches also failed on persistent and deep persistent layers. At lower elevations where precipitation fell as rain, loose wet avalanches to size 2 were also observed. With ongoing loading from new snow and wind, I expect ongoing storm slab activity with the potential for deeper destructive releases.

Snowpack Summary

Ongoing heavy snowfall (with rain below approximately 1200 m) and extreme southwest winds continue to build fresh deep and dense storm slabs. A rain crust and/or surface hoar layer buried mid-January is buried about 100cm below the surface. This weakness became reactive with recent heavy loading, and has been responsible for much of the recent large avalanche activity. The November crust near the bottom of the snowpack is generally well bonded, but has woken-up in some cases with intense loading and warm temperatures throughout the past week. There is still potential for very large and deep avalanches.

Regions covered