Avalanche Forecast

Issued: Dec 3rd, 2014 8:26AM

The alpine rating is moderate, the treeline rating is moderate, and the below treeline rating is low. Known problems include Wind Slabs and Persistent Slabs.

ghelgeson, Avalanche Canada

Kootenay Boundary.

Riding north of Nelson? Take a look at the South Columbia forecast. Please email your observations to forecaster@avalanche.ca

Summary

Confidence

Poor - Due to the number of field observations

Weather Forecast

Synopsis: Dry and cold northwest flow is giving way to rather mild southwest flow. Cold will likely remain entrenched in the valley bottoms for another few days, while alpine temps are already on the rise. I dont see any hogs in the flow just yet, but there is a small trough that should produce a bit of snow this weekend. Thursday: Freezing Level: Valley Bottom; Precipitation: 2-5mm | 1-8cm; Wind: Treeline: Light, SW | Ridgetop: Moderate, SWFriday: Freezing Level: 500m; Precipitation: 2-8mm | 2-10cm; Wind: Treeline: Light, SW | Ridgetop: Moderate, SWSaturday: Freezing Level: 600m; Precipitation: 3-8mm | 2-10cm; Wind: Treeline: Light, S/SW | Ridgetop: Strong, SW

Avalanche Summary

No new avalanche activity to report.

Snowpack Summary

This forecast is based on very limited data. The snowpack north of Nelson is a different beast than the rest of the forecast region. If you're recreating north of Nelson, then current conditions more closely mirror those of the South Columbia. Check out that forecast to get a feel for the more complex snowpack and the associated Persistent Slab Problem. In the north it appears that two buried weak layers may be problematic: The mid November surface hoar/facet/crust combo down 70 - 90 cm and the weak sugary snow (large facets) near the ground. Little is known about the particulars of this setup, more observations would be great!In the southern portion of the region observations indicate that the snowpack is much more homogeneous and strong. There have been no reports of deeply buried weak layers. The Black Friday storm came in wet and finished cold. As a result, the structure consists of 15 - 25 cm of cold snow on top of a 2 - 6 cm supportive pencil/knife hard crust which was been observed as high as 2100. This crust could act as a bed surface in the future, but for now it appears to be bridging any deeper weaknesses.

Problems

Wind Slabs

While they should be easy to avoid, pay attention to how the snow feels as you travel through the terrain, there may be the odd wind slab hiding out in wind exposed terrain.

Be cautious as you transition into wind affected terrain.>Be alert to conditions that change with elevation.>Dig down to find and test weak layers before committing to a line.>

Aspects: North, North East, East, South East, South.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

1 - 3

Persistent Slabs

Limited to the northern half of the forecast area, the persistent slab problem has the potential to ruin your winter before it starts. Avalanches initiating high in the snowpack may step down resulting in a surprisingly large avalanche.

Be aware of the potential for large, deep avalanches.>Be aware of thin areas that may propogate to deeper instabilites.>Avoid shallow snowpack areas where triggering is more likely.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 5

Valid until: Dec 4th, 2014 2:00PM