Avalanche forecast

North Columbia

Apr 14 – 15, 2018Avalanche Canada
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Avalanche danger

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

Snow and wind will continue to build storm slabs at all elevations. Expect these to be touchy in wind loaded areas and where a crust has been buried.  Be aware of potential for loose wet slides and cornice failures with sun and warming.

Avalanche problems

  • Cornices

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2–4
    Large cornice failures have been reported in the past week. A cornice collapse may also have the potential to trigger a deep weak layer resulting in a very large avalanche.

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–2.5
    Recent widespread storm slabs may be poorly bonded to the crust below. Be very cautious with wind-loaded and cross-loaded slopes at treeline and above where these slabs may be especially deep and reactive.

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible - Likely
    Size
    1–2.5
    Warming temperatures and a bit of sun may destabilize surface snow and initiate loose wet avalanche activity, especially on steep south facing features.

Confidence

Moderate - Intensity of incoming weather systems is uncertain

Weather Forecast

TONIGHT: Cloudy, flurries. Accumulation 5-15 cm. Ridge wind light to moderate, southwest. Alpine temperature near -7. Freezing level 700 m.SUNDAY: Cloudy, flurries. Accumulation 2-8 cm. Ridge wind light, southeast. Alpine temperature near -5. Freezing level 1700 m.MONDAY: Mostly cloudy, light flurries. Accumulation trace. Ridge wind moderate to strong, southeast. Alpine temperature near -5. Freezing level 1900 m.TUESDAY: Cloudy, flurries. Accumulation 10-20 cm. Ridge wind light, northwest. Alpine temperature near -5. Freezing level 1600 m.

Avalanche Summary

On Friday there were reports of a skier-triggered wind slab (size 1) on a steep, cross-loaded, southeast-facing slope at 2700 m.  As well as a size 1.5, skier-triggered loose, wet release release in moist snow above a crust on a west-facing slope at 2000 m. Also on Friday a large cornice collapsed on a southeast aspect at 2500 m, with several 'bus-sized' blocks observed in the debris.Thursday there were reports from Glacier National Park of a size 4 wind slab that occurred overnight and is thought to have been cornice triggered on a north aspect at 2800 m.Wednesday there was a report of a natural cornice failure that resulted in a size 2.5 wind slab release (50 cm deep and 200 m wide) on a northeast aspect at 2600 m, north of Glacier National Park.And on Tuesday in the neighboring Glacier National Park, natural loose wet avalanches size 2.5 to 3 ran on all aspects between 1950 and 2700 m.

Snowpack Summary

About 15-25 cm of new snow overlies a crust on all aspects to at least 2300 m (and possibly higher on south aspects). While 30-50 cm of storm snow can be found at higher elevations in the alpine. There are now a few different crusts in the upper 50 cm of the snowpack, with only the upper, most-recently buried crust posing a concern with new storm snow at upper elevations.There is some lingering concern around the mid-March Persistent Weak Layer (PWL) in the alpine where it is found 70 to 120 cm below the surface. This buried crust/surface hoar interface was widely reactive but has not produced any avalanche in the past week. It is likely trending towards dormancy, but we need to keep it in the back of our minds as it is capable of producing large avalanches should it be triggered (think step-down from a surface avalanche or a cornice collapse).Deeper persistent weak layers from December and January are generally considered dormant at this time but may be starting to become reactive to large triggers, such as a cornice collapse.

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