Avalanche Forecast

Issued: Apr 16th, 2015 4:00PM

The alpine rating is below threshold, the treeline rating is below threshold, and the below treeline rating is below threshold. Known problems include Wind Slabs, Loose Wet and Cornices.

stephen holeczi, Parks Canada

Banff Yoho Kootenay.

There is the potential for freezing levels to 2600m Friday. Start early and watch for rapid heating. SH

Summary

Weather Forecast

Cloudy with freezing levels to valley bottom for Friday AM, but will rise to 2600m by the afternoon. We expect some cloud cover late in the afternoon and the potential for light flurries. Winds will be moderate from the West. Temperatures should cool for the weekend.

Snowpack Summary

The recent 30-50cm of storm snow has been blown into wind slabs up to 60cm thick in the alpine by previous strong winds. These overly a variety of harder surfaces. Cornices are a major concern and seem to be waking up the basal facets in isolated areas if they have enough mass.

Avalanche Summary

Less natural activity was noted today as winds kept things generally cool. Isolated whumpfing was still noted in the Observation Sub Peak area Thursday and was likely due to new wind slabs sitting over suncrust. On Wednesday, a large cornice release triggered a size 3 avalanche on the basal facets in the Sunshine backcountry.

Confidence

Problems

Wind Slabs

Wind slabs will be less reactive by the weekend with cooler temperatures, but watch for how these are bonding to the harder surfaces below Friday, especially as the day heats up.

Be careful with wind loaded pockets, especially near ridge crests and roll-overs.

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

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 2

Loose Wet

With higher freezing levels forecast for Friday, we may see an increase in solar triggered avalanche activity. It is possible that wet slides could initiate the basal facet layers if they have enough mass.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Cornices

Many large cornices have formed recently, and there have been numerous reports of cornice failures over the last week. In isolated events these have been enough mass to trigger the deep basal facets.

Extra caution needed around cornices with current conditions.

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

Elevations: Alpine.

Likelihood

Possible - Likely

Expected Size

1 - 3

Valid until: Apr 17th, 2015 4:00PM