Avalanche Forecast

Issued: Mar 28th, 2015 4:00PM

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

snow safety, Parks Canada

Banff Yoho Kootenay.

The amount of overnight freeze and solar input will be key to the danger ratings Sunday. If it does not freeze, danger ratings will be higher than listed, especially at treeline and below. SH

Summary

Weather Forecast

Freezing levels are forecast to drop to valley bottom Sunday morning, with afternoon freezing levels to 2100m. The Banff/Sunshine region could see sunny periods, and the Northern regions should be mostly cloudy. Moderate to Strong W winds Sunday and trace amounts of precipitation.

Snowpack Summary

Rain below 2000-2200m Saturday. Up to 15cm high density snow amounts in the alpine Saturday. Treeline elevations are taking the brunt of the heat/rain as some areas below treeline are below threshold and the alpine stayed at or below freezing. The mid pack at treeline and above still has weaker basal facets and depth hoar as a concern.

Avalanche Summary

Many loose wet avalanches to size 2 at treeline and below were noted Saturday through the forecast region due to Friday's heat, and Saturday's rain.

Confidence

Freezing levels are uncertain on Sunday

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 windslabs. 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.

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 29th, 2015 4:00PM