Avalanche forecast

Banff Yoho Kootenay

Apr 18 – 19, 2018Parks Canada
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Avalanche danger

Fri
Sat
Alpine
4 · High
Treeline
4 · High
Below
4 · High
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Highlights

Danger rating based on the highest rating of the day in relation to temperatures, and we expect an avy cycle on Thursday. Avalanche control on Mt. Whymper, Simpson, Vermillion, Wardle, and Mt. Bourgeau Thursday. No activities in these locations.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–2.5
    20-50 cm of storm snow has fallen over the past few days with the greater amounts near the divide. Increased SW wind Tuesday afternoon loaded lee terrain creating reactive windslabs producing large results Wed.  See avalanche discussion.

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible - Likely
    Size
    1–2.5
    While it has been several days since there have been any confirmed events directly associated with the March 15 crust, other temperature crusts have now become buried in similar locations and are providing a good sliding layer for the new storm snow.

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Very Likely
    Size
    1–2.5
    High solar input Thursday will increase the avalanche danger at all elevations. Watch locally for exposure to sun and how it is affecting the terrain you are on.

Weather Forecast

Mainly sunny conditions Thursday will see lots of solar input which will finally bring some spring temperatures to the region.  Light winds and no snow in the forecast. Next week looks like a very warm week which will bring a dramatic spike in the avalanche danger.  Stay tuned.

Snowpack Summary

Up to 50 cm of storm snow near the divide affected by strong SW winds Tuesday evening. Several buried temperature crusts exist to 2000m on all aspects and to ridge tops on solar slopes, including the Mar 15 sun crust down 35-50 cm in the alpine. Moist snow at lower elevations, with the entire snowpack becoming moist near valley bottom.

Avalanche Summary

Some size 2 wind slabs reported at sunshine with explosives.  Avalanche control on Mt. Bosworth Wednesday produced avalanches to size 3 with good propagations up to 200m wide, and further West a size 3.5 out of Emerald Lake slidepath occurred last evening.

Confidence

Freezing levels are uncertain on Thursday

Regions covered