Avalanche forecast

Sea To Sky

Apr 20 – 21, 2017Avalanche Canada
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Avalanche danger

Sat
Sun
Alpine
3 · Considerable
Treeline
2 · Moderate
Below
2 · Moderate
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Highlights

Warm temperatures and strong sunshine will combine to promote reactivity in a range of avalanche problems on Friday.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–2
    Recent southeast winds redistributed our new snow into thick wind slabs on leeward aspects in the alpine. Strong solar effect will promote the reactivity of these wind slabs on Friday.

  • Cornices

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible - Likely
    Size
    2–3
    Where cornices exist, they are unstable and should be avoided. Falling cornices are hazard in themselves but they can also trigger large avalanches. Strong solar radiation will be weakening cornices on Friday.

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely - Very Likely
    Size
    1–2
    Warm temperatures and strong sunshine will promote loose wet avalanches throughout the day on Friday, especially in steep terrain. Loose wet slides may occur naturally or with a human trigger.

Confidence

Moderate -

Weather Forecast

Friday: A mix of sun and cloud. Light to moderate southeast winds. Freezing level to 2200 metres with alpine temperatures around 0 to +1.Saturday: Cloudy with flurries bringing 5 cm of new snow to higher elevations by evening. Moderate southeast winds. Freezing level dropping to 1700 metres over the day with alpine temperatures around 0 to -2.Sunday: Mainly cloudy with scattered flurries and a trace of new snow. LIght south winds. Freezing level to 1700 metres with alpine temperatures of -4.

Avalanche Summary

Reports from Wednesday include observations of explosives triggered storm slabs reaching Size 1.5 in the Whistler area. Crown depths averaged 20 cm.Very touchy conditions were reported in the Whistler backcountry on Tuesday, with skiers remote-triggering soft slab avalanches, running on the Easter crust. On Monday, a Size 2 avalanche was triggered on a west aspect in the Tantalus range near 2000m. See here for the excellent and informative MIN report.On Sunday, skiers triggered a Size 1.5 slab avalanche in a northwest facing couloir in the alpine near Whistler. See here for their MIN report.

Snowpack Summary

Stormy weather over the beginning of the week has brought about 30-40cm of new snow to the Sea to Sky mountains, with this precipitation falling as rain below about 1400m. Strong southeast winds over the same time period created pockets of reactive wind slab (up to 50 cm thick) in the alpine and exposed features at treeline, in addition to building fragile new cornice growth. A melt-freeze crust (the 'Easter crust') exists below this new snow on south aspects at all elevations. The new snow has begun to show signs of an improving bond with this crust. The mid and lower snowpack are generally well settled and strong.

Regions covered