Avalanche forecast

Sea To Sky

Mar 13, 2022Avalanche Canada
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Archived · expired 5 years ago

Avalanche danger

Tue
Wed
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
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Highlights

Watch for pockets of wind slab at upper elevations. Don't forget about a buried weak layer that remains triggerable.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–1.5

    New wind slabs have started to form as new snow accumulates with southwest wind. They may be small but reactive if they bond poorly to the old surface.

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1.5–2.5

    A weak layer of faceted grains above a hard melt-freeze crust may be found around 40 to 80 cm deep. Last week this layer produced large avalanches. The problem is most prevalent on north to northeast aspects between 1600 m and 2100 m.

Confidence

Moderate -

Weather Forecast

Saturday night: Cloudy with snowfall, accumulation around 5-10 cm, 20-30 km/h south wind, alpine temperature -6 C. Freezing level 1000 m.

Sunday: Cloudy with scattered flurries, 10-20 km/h southwest wind, alpine temperature -5 C. Freezing level 1500 m.

Monday: Cloudy with snowfall, accumulation 15-30 cm, 40-60 km/h southwest wind, alpine temperature -5 C. Freezing level 1500 m.

Tuesday: Cloudy with snowfall, accumulation 20-40 cm, 30-50 km/h southwest wind, alpine temperature -5 C. Freezing level 1400 m.

Avalanche Summary

On Saturday, a few skier controlled size 1 loose dry and soft wind slab avalanches were reported.

Persistent slab activity has dwindled since last week. The most recent activity was on Tuesday when two avalanches were triggered by riders on northeast aspects at treeline and alpine elevations, similar to the trend of previous avalanches. It remains possible that humans could trigger this layer, where it exists.

Snowpack Summary

Small amounts of new snow and southwest wind have likely formed small wind slabs in lee terrain features. The snow accumulates over a thin layer of variably wind affected, faceted snow or surface hoar that overlies a hard melt-freeze crust found on all aspects below around 1500 m and on sun-exposed slopes into the alpine. The snow sits on previously wind-affected and faceted snow on shaded slopes above 1500 m.

Around 40 to 80 cm deep, a weak layer of sugary faceted grains may be found above a melt-freeze crust that formed in February. This layer has produced about one or two human-triggered avalanches per day over the past week. Activity has been most prevalent on north to northeast aspects between 1600 m and 2100 m. Check out this forecaster blog for more info.

There are no deeper concerns at this time.

Terrain and Travel

  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • Closely monitor how the new snow is bonding to the old surface.
  • Be aware of the potential for large avalanches due to the presence of a persistent slab.
  • Use extra caution around cornices: they are large, fragile, and can trigger slabs on slopes below.

Regions covered