Avalanche Forecast

Issued: Nov 29th, 2011 9:31AM

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

Avalanche Canada swerner, Avalanche Canada

Summary

Confidence

Fair - Due to limited field observations

Weather Forecast

Wednesday: Clearing is expected as the low pressure system that was dominating our weather slides east into Alberta. Freezing levels will rise to over 1300m during the day under clear skies and return to valley bottom at night.Thursday: Expect a few clouds with temperatures tapping out around -2 C @ 1500m. Freezing levels will rise to around 500 m. Winds in the alpine will be at 20 – 35 km/hr out of the northwest. Winds die down as you drop in elevation; expect light winds out of the south west @ treeline.

Avalanche Summary

No current avalanche observations from the field. I suspect there may have been a natural cycle later Sunday into Monday as the last storm came through. At this point we have extremely limited observations from the Kootenay-Boundary region. 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 -150cms. There are locations in the alpine that have just over 200cm. Recent snow pack observations are indicating the late October rain crust is present in the alpine elevations and down approximately 120cm. This crust is said to be up to 5mm in thickness with predominate faceting below it. For the moment the crust seems to be bridging over the facets below, with a settling snowpack above. There have been evidence large avalanches running to ground in surrounding regions last Friday. I suspect this may have also occurred in the Kootenay Boundary but have no solid evidence. We should keep this layer in the back of our minds as we move forward. Sunday's big system produced but a few centimeters 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. 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 have created new wind slabs on lee slopes and cross-loaded terrain features. Wind slab releases may step down to deeper weak layer producing large avalanches, if that weakness exists.

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

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.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

1 - 3

Valid until: Nov 30th, 2011 8:00AM