Avalanche Forecast

Issued: Dec 13th, 2015 8:06AM

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

rbuhler, Avalanche Canada

Kootenay Boundary.

The weekend's storm instabilities are expected to linger for a few days. Use extra caution on steep south-facing slopes during the afternoon if the sun is out in full force.

Summary

Confidence

Moderate - Timing or intensity of solar radiation is uncertain

Weather Forecast

A ridge of high pressure will bring dry and partly sunny conditions on Monday. Freezing levels are expected to be around 1000m and ridgetop winds should be light from the north. Increased cloudiness is expected for Tuesday with freezing levels falling to near valley bottom and light to moderate alpine winds from the NW. Dry and sunny conditions are expected for Wednesday.

Avalanche Summary

No new natural avalanches have been reported since Wednesday. On Saturday, explosives triggered storm slabs up to size 2. These slabs were 5-15cm thick and were running on the thick melt-freeze crust.

Snowpack Summary

10-30cm of recent snowfall sits over a thick rain crust. This crust is being reported as high as 2400m. At treeline elevation this crust is thick and supportive, and should be capping any deeper weaknesses. The weak layer from early December has recently become inactive, likely due to all the moisture in the snowpack. The mid and lower snowpack is reported to be moist or wet to the ground at treeline elevations.

Problems

Storm Slabs

Recent storm instabilities may remain reactive to human-triggering, especially in the leeward side of ridge crests and in wind-loaded chutes.

Be cautious as you transition into wind affected terrain.>Use ridges or ribs to avoid pockets of wind loaded snow.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Persistent Slabs

The weak layers buried in early-Dec and mid-Nov in the middle of the snowpack have become difficult to trigger but are still a concern in isolated areas. Heavy triggers like cornices or avalanches stepping down could result in very large avalanches.

Caution on open slopes and convex rolls at and below treeline where buried surface hoar may be preserved.>Dig down to find and test weak layers before committing to a big line.>Caution around convexities or areas with a thin or variable snowpack.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

3 - 5

Valid until: Dec 14th, 2015 2:00PM