Avalanche Forecast

Issued: Apr 1st, 2016 4:05PM

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

Lisa Paulson, Parks Canada

Banff Yoho Kootenay.

Start early and end early! If the sun appears, expect the avalanche hazard to rapidly rise towards HIGH, especially if the winds also decrease.

Summary

Weather Forecast

For Saturday and Sunday increased cloud and wind is forecast and will help keep things a little cooler. Freezing levels will only drop to 2000 m tonight and climb to 2400 m Saturday. If the sun comes out expect the avalanche hazard to rapidly rise towards HIGH.

Snowpack Summary

After 2 hot days, expect surface crusts on all aspects (expect high due North aspects) with moist snow underneath. Crusts will rapidly break down with daytime heating or sun exposure. In many places the snowpack is sitting on a deep persistent of facets that has been avalanching to size 3.5 with solar heating over the past 2 days.

Avalanche Summary

Another day of widespread natural activity. Numerous deep persistent avalanches to size 2.5 on N-NW aspects in and loose wet avalanches to size 2 on solar aspects. On Thursday, there were solar induced natural avalanches in Kootenay today to size 3.5 where the sun has been out all day. Many of these were stepping to ground.

Confidence

Problems

Deep Persistent Slabs

Deep facet layers remain very weak & stressed by the recent heat. Give it some time - continue to avoid large open slopes, steep slopes and be wary that you can trigger this problem from a long distance away - the slab is stiff and it propagates far.

Avoid slopes when the solar radiation is strong, especially if they have large cornices overhead.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

2 - 4

Loose Wet

If the sun comes out, the snow pack is warm and will rapidly deteriorate and expect slush style avalanches to be running in gullies, from cliffs and on steep slopes facing the sun or in below treeline terrain.

If triggered the loose wet sluffs may step down to deeper layers resulting in large avalanches.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 2

Cornices

Cornices are large. Give them a wide berth on ridge crests, as they can pull back a long way when they fail and may trigger avalanches below. If you need to travel under cornices, move quickly and think twice if there is significant heating.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

2 - 3

Valid until: Apr 2nd, 2016 4:00PM