Avalanche forecast

Purcells

Apr 4 – 5, 2016Avalanche Canada
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Avalanche danger

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

Cloud and slight cooling should help temporarily drop avalanche danger on Tuesday, but continue to exercise caution if the sun appears during the day.

Avalanche problems

  • Cornices

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    3–6
    Cooler temperatures and more cloud might make cornices less likely to fail naturally, but I would still give droopy overhanging cornices a wide berth. 

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely - Possible
    Size
    3–6
    Brief and slight cooling on Tuesday could make buried persistent weaknesses less sensitive to triggering, but keep this problem on your radar for later in the week when the heat and sun return.

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–2
    A bit of fresh snow and a chance of sunny breaks could lead to renewed loose wet activity on sun-exposed slopes. 

Confidence

Moderate

Weather Forecast

TUESDAY: Mainly cloudy with a chance of showers/flurries and afternoon sunny breaks. The freezing level dips to around 1400 m overnight and rises to 1600-1800 m during the day. Winds are moderate to strong from the W-NW. WEDNESDAY: Clearing. The freezing climbs to 2600 m and winds are light to moderate from the West. THURSDAY: Mainly sunny. The freezing level continues its ascent up to 3200 m. Winds should ease to light and variable.

Avalanche Summary

Recent soaring temperatures and strong sunshine have resulted in significant natural avalanche activity for the past several days. Slab avalanches to size 2.5 have been very common over the last few days on almost all aspects (the exception being high elevation north). Large loose wet avalanches and cornice falls have also been a common theme. Cloud cover and slight cooling might halt natural activity briefly this week.

Snowpack Summary

Recent warm temperatures, weak/non-existent overnight refreeze, and rain have moistened the upper snowpack at all elevations. Elevations above 2000 m may getting snow on Monday (5-10 cm is possible), and a cooling trend could create a crust at or near the surface down to around 1500 m. Below 1400 m, the snowpack is likely fully isothermal. The March 22nd rain crust is present to around 2000 m, but the warm temps have likely allowed the overlying 30 to 40 cm of snow to bond well. Once it freezes, this layer should not be much of a concern. The late February persistent weak layer is now down 40 to 100 cm below the surface, and may

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