Avalanche Forecast

Issued: Nov 28th, 2011 8:30AM

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

Avalanche Canada jlammers, Avalanche Canada

Summary

Confidence

Poor - Due to limited field observations

Weather Forecast

Light to moderate precipitation is forecast for tuesday afternoon with moderate southwest winds and freezing levels reaching 1200m.On wednesday and thursday a ridge is expected to dominate the area bringing clear skies, light to moderate northwest winds and freezing levels at or near surface.

Avalanche Summary

Numerous size 3 natural avalanches were reported north of the region on friday on a suspected early season crust that has been reactive in a few regions throughout the province. At this point we have extremely limited observations from the Kootenay-Boundary region; but the recent weather has been sufficient to produce significant avalanche activity at treeline and in the alpine. If you have any avalanche observations to report, please email us at: forecaster@avalanche.ca.

Snowpack Summary

Generally there is about 150 cms in the alpine, and treeline has been showing some variability between 50 -150 cms. There are locations in the alpine that have 200 cms plus already. On friday we received new information from the Selkirks south of Revelstoke that there was indeed a major avalanche cycle up to size 3.5 during the last storm, but it appears that most of the avalanches were sliding on a layer that is near the ground; perhaps a rain crust from October. This crust has also been highly reactive in the Lizard Range to the east. At this point we have heard no reports of this lower layer existing in the Kootenay-Boundary region; however, I think that we should at least be curious about the possibility of its existence as we gather information from data-sparse areas.Sunday's big system produced but a few centimetres of snow with freezing levels rising to 1800m, but winds were strong from the southwest. In the mid and upper snowpack, expect wind slabs and storm slabs resulting from this wind event and last weeks storms. With tuesday's forecast snow and wind, expect further wind and storm slab development.We hope to get some more information soon, as operators start getting out into the field. Any info from the field is welcome in our office. Let me know what you're seeing out there! forecaster@avalanche.ca

Problems

Wind Slabs

An icon showing Wind Slabs
Strong winds and warming temperatures will create new wind slabs on lee slopes and cross-loaded terrain features.

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 3

Storm Slabs

An icon showing Storm Slabs
Slabs have been developing over the past few storms. These slabs are probably averaging 50-80 cms. We have very little information regarding avalanche activity in this region.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

1 - 3

Valid until: Nov 29th, 2011 8:00AM