Avalanche Forecast

Issued: Mar 29th, 2015 7:47PM

The alpine rating is considerable, the treeline rating is moderate, and the below treeline rating is moderate. Known problems include Loose Wet, Wind Slabs and Deep Persistent Slabs.

patrick jerome, Parks Canada

Banff Yoho Kootenay.

High winds in the alpine have generated windslabs in the immediate lee as well as cornices. Rain saturated snow to treeline has weakened the strength of the upper snowpack so avoid any steep terrain where the snowpack is isothermal.

Summary

Weather Forecast

Rising freezing levels and saturated air will generate heavy snow across the mountains of western BC. After dipping below 1500 meters Saturday morning in the south, the freezing level rise to, and then hover near 2000 meters tonight through Monday afternoon. For the rest of the week, the freezing level will remain near 1500 to 2000 meters.

Snowpack Summary

Rain saturated upper snowpack to 2000 meters on all aspects. Moderate to strong winds in the alpine forming wind slabs up to 30cm in the immediately lee on east through north aspects. The mid pack above tree line is well settled which overlies basal facets and depth hoar.

Avalanche Summary

Lake Louise and Sunshine reported significant cornice growth and several wind slabs up to size 1.5 being easily triggered on the March 28th crust interface. Wind slabs were far more stubborn to trigger on north aspects due warm temps and rapid settlement.

Confidence

Intensity of incoming weather systems is uncertain on Monday

Problems

Loose Wet

Avalanche activity will depend upon overnight freeze and solar input Sunday. There is a lot of heat and moisture in the lower elevation snowpack.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Wind Slabs

There is generally 10-20 cm available for transport and moderate to strong SW wind continues to build wind slabs. With a good freeze Sunday these will become less sensitive, but will be found in immediate lees or ridge crests.

Use caution in lee areas. Recent wind loading have created wind slabs.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Deep Persistent Slabs

The lower half of the snowpack is weak due to the presence of basal facets and depth hoar. Loose wet avalanches could initiate these deeper layers.

Be aware of thin areas that may propogate to deeper instabilites.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

2 - 3

Valid until: Mar 30th, 2015 4:00PM