Avalanche forecast

Kootenay Boundary

Dec 5 – 6, 2014Avalanche Canada
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Avalanche danger

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

Riding north of Nelson? Take a look at the South Columbia forecast too. Please email your observations to [email protected]

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    3–5
    There are a few deeply buried weak layers in the snowpack. Not a lot is known about this structure, but it's likely that trigger-ability will increase as it's snowing and blowing.

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible - Likely
    Size
    1–3
    5- 15 cm of fresh storm snow is coming to rest on either crust, surface hoar or snow that has become weak with the recent cold temps. Add in SW winds, and it's likely that shallow yet sensitive wind slabs will form in exposed terrain.

Confidence

Poor - Due to the number of field observations

Weather Forecast

Synopsis: A pattern shift is underway as dry and cold northwest flow gives way to rather mild southwest flow. Storm totals through the weekend look rather modest, but the door appears to be open to a succession of storms through the middle of next week.Friday: Precipitation: 1-3mm | 2-5cm; Wind: Moderate, SWSaturday: Freezing Level: 600m; Precipitation: 3-12mm | 4-15cm; Wind: Treeline: Light, SW | Ridgetop: Moderate/Strong, SW Sunday: Freezing Level: 800m; Precipitation: Trace: Treeline: Light, SW | Ridgetop: Moderate, SWMonday: Freezing Level: 1000m; Precipitation: 0-3mm | 0-5cm; Wind: Treeline: Light, SW | Ridgetop: Moderate, SW

Avalanche Summary

We received an observation of a small natural avalanche from the Kokanee Glacier Park on an east facing slope just below treeline. This avalanche failed on the early November crust/facet combo near the ground. Subsequent testing produced inconsistent sudden planar results. While it's technically just north of this region, I suspect that this is a pretty good example of the snowpack structure in the region north of Nelson.

Snowpack Summary

This forecast is based off a very limited data set. The snowpack north of Nelson is a different beast, if you're riding in that part of the region, check out the South Columbia forecast to get a feel for the more complex snowpack and the associated persistent slab problem.Across the region the Black Friday storm came in wet and finished cold. This left a supportive (pencil/knife) crust 2 - 8cm thick which is present to around 2000m. 15 - 30 cm of snow from the tail end of that storm now rests on this crust. Winds have been pretty mild since the storm, but I suspect you can find the odd wind slab in exposed terrain.In the north it appears there are three layers of concern: The late November crust at or just below the surface; the mid November surface hoar/facet/crust combo down 70 - 90 cm; and the early November hard crust/facet combo near the ground. In the southern portion of the region observations indicate that the snowpack is more homogeneous and strong, but the early November hard crust/facet combo is present in some locations. Just how widespread this is, I don't know. We'd be stoked to see your observations this weekend! 

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