Avalanche forecast

Sea To Sky

Apr 15 – 16, 2018Avalanche Canada
View on map
Archived · expired 8 years ago

Avalanche danger

Tue
Wed
Alpine
3 · Considerable
Treeline
2 · Moderate
Below
1 · Low
Open full map

Highlights

Wind slabs formed early-weekend have been reactive to human traffic. Snowfall on Monday could build new slabs, which may not bond well to variable underlying surfaces.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible - Likely
    Size
    1–2.5
    Strong south winds redistributed recent snow.  Slabs up to 1 m thick are found in lee terrain features.  They have been reactive to human and natural triggers.  Watch your overhead exposure, as cornices could trigger slabs on slopes below.

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely - Possible
    Size
    2–3
    Professionals are still travelling cautiously due to a weak layer buried 60 to 140 cm.  Be particularly cautious around upper treeline and alpine terrain on shady aspects, where this layer is most likely to be a problem.

Confidence

Moderate - Intensity of incoming weather systems is uncertain

Weather Forecast

MONDAY: Cloudy with light snowfall, accumulation 5 to 15 cm, light to moderate southeast winds, alpine temperature -5 C, freezing level 1400 m.TUESDAY: Cloudy with light snowfall, accumulation 2 to 5 cm, light west winds, alpine temperature -6 C, freezing level 1300 m.WEDNESDAY: Mostly cloudy, light southwest winds, alpine temperature -7 C, freezing level 1300 m.

Avalanche Summary

On Saturday, wind slabs and cornices were reactive to explosives, producing small avalanches generally in wind-loaded alpine and treeline terrain.

Snowpack Summary

30 to 40 cm of recent snow has been redistributed by strong south winds, forming reactive wind slabs up to 1 m deep in lee terrain features.  Sun, rain, and warm air temperatures on Sunday moistened the snow surface, which will freeze into a melt-freeze crust on all aspects up to at least 1800 m.  Snowfall on Monday will fall on these surfaces.  Ridgelines are heavily corniced and if they fail they could trigger slabs on slopes below.A weak layer consisting of surface hoar, facets, and/or a melt-freeze crust from late March is now buried about 60 to 140 cm. Although this layer is spotty in its distribution and avalanches haven’t been reported on it since early April, professionals are treating it seriously and avoiding terrain because of it.  It is mostly likely to be problematic on west, north, and east aspects between 1900 m and 2250 m.Below this, the snowpack is well-settled and strong.

Regions covered