Avalanche forecast

South Rockies

Apr 8 – 9, 2015Avalanche Canada
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Avalanche danger

Fri
Sat
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
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Highlights

Daytime warming will be driving the Avalanche Danger on Thursday. Watch for conditions that change with aspect, elevation and time of day.For details on how we issue Spring Danger Ratings, check out the latest Forecaster Blog.

Avalanche problems

  • Cornices

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–4
    Large cornices at ridgetop may fail under the weight of a person. Remember that destructive cornice falls become more likely during periods of warming and solar radiation.

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible - Likely
    Size
    1–2
    Watch for pushy loose wet avalanche activity on sun exposed slopes. Loose wet avalanches can entrain mass quickly and travel long distances.

Confidence

Fair - Due to the number of field observations

Weather Forecast

On Thursday and Friday morning, a dry ridge will maintain sunny skies and strong diurnal temperatures swings. Increased cloud should develop throughout the day on Friday. By Friday evening, we can expect light snow (up to 5cm) and cooler temperatures which should continue into Saturday. Daytime freezing levels should hover around 2300m on Thursday, 2000m on Friday and about 1500m on Saturday. Ridgetop winds will be light on Thursday, and then become strong from the southwest with Friday and Saturday's system.

Avalanche Summary

Observations are becoming more limited as we enter into spring. If you're out in the mountains, please consider posting your observations to our webpage using the Mountain Information Network. With freezing levels rising and lots of sun expected on Thursday, lots of natural sluffing is expected from steep sun-exposed slopes. Cornices will become weaker and may fail naturally. Thin wind slabs may also be sensitive to human triggering on isolated high elevation, lee slopes.

Snowpack Summary

10-20cm of recent snow overlies a widespread and supportive melt-freeze crust. In some areas, winds may have redistributed the surface snow resulting in wind slab formation in the alpine and exposed areas at treeline. Large cornices exist in the alpine and may become weak with daytime warming. The mid-March rain crust is down 35 to 70cm and has shown a good bond with snow above. Old persistent weak layers are still intact in the mid and lower snowpack and there may be potential for these layers to wake up with a big cornice fall, sustained warming and/or a significant rain event.

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