Avalanche forecast

South Rockies

Apr 1 – 2, 2015Avalanche Canada
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Avalanche danger

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

Warmth remains the primary driver of avalanche hazard as we shift into a more spring like pattern. Minimize your exposure to large slopes if the snowpack is becoming moist or wet.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible - Likely
    Size
    1–3
    Upper elevation winds have been generally out of the west at slab-forming speeds for the past 72 hours. Stay on guard for fresh and potentially touchy wind slabs, especially if your travel plans include terrain immediately lee of ridge-crest.

  • Cornices

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–4
    Large, vulnerable and dangerously heavy chunks of snow hang precariously over many ridge-lines. While cornice failure is problematic enough on its own, don't discount the ability for falling chunks of cornice to release bigger slab avalanches.

Confidence

Fair

Weather Forecast

Thursday: Freezing starting near 1000m, rising to about 1600m in the afternoon. Partly cloudy skies. Light variable winds at all elevations. No significant precipitation expected.Friday: Freezing level starting at valley bottom, rising to about 1700m throughout the day. Mostly clear skies. Moderate SW winds all elevations. No significant precipitation expected.Saturday: Freezing level hovering around 1500m. Moderate SW winds at treeline, strong SW winds at ridgetop. Scattered cloud. No significant precipitation.

Avalanche Summary

No new activity to report from Tuesday. On Monday a few large avalanches were reported: Our field team was in the Crown Mountain area where they noticed a large slab avalanche on an extreme E/NE face that was likely triggered by cornice fall. In the neighboring Waterton region cornice failure resulted in two large avalanches that stepped down to the mid-February interface on NE facing features at 2400m. On Saturday in the neighboring Lizard Range cornice fall produced a size 2.5 avalanche.

Snowpack Summary

Both Monday and Tuesday brought good overnight temperature recovery to the region with temps getting down to +0.8c at 960m. These colder temps are forming a surface crust that should become supportive if it isn't already. On Wednesday ridge-top transport of snow was observed which is likely resulting in wind slab formation in the alpine. The snowpack is reportedly isothermal as high as 2000m at this point and even the highest elevations are probably not far off. 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.

Regions covered