Avalanche Forecast

Issued: Mar 30th, 2016 4:00PM

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

grant statham, Parks Canada

Banff Yoho Kootenay.

Conditions are poor. The mountains are in the midst of a major transition from winter snowpack to spring melt/freeze cycle, and for the next few days the snowpack is not expected to freeze and gain any strength. Avoid avalanche terrain.

Summary

Weather Forecast

A very strong "blocking ridge" of high pressure is stationary over Western Canada, resulting in clear skies and very warm temperatures with some residual cloud and snow/rain expected near and east of the Continental Divide. Thursday will be 10-15 degrees with cloud cover in eastern areas. Cloudy skies will prevent the snow from freezing overnight.

Snowpack Summary

The snowpack is in transition between winter and spring, and is a poor example of both. Wet and isothermal snow below 1800m; moist snow above that with no freeze expected for Thursday morning. This warm slab of snow overlies a weak, facetted snowpack and will fail easily - particularly when the sun comes out, even if it's just for a few minutes.

Avalanche Summary

Numerous wet snow avalanches up to size 2 observed in the Lake Louise area, and one size 2 slab on a north aspect at 2400m that failed on deep facets.

Confidence

Problems

Deep Persistent Slabs

Deep facet layers remain very weak, especially in thin or rocky areas. Avoid large open slopes, steep slopes (>30 degrees) 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

Likely

Expected Size

2 - 4

Loose Wet

This problem is widespread, and expect slush style avalanches to be running in gullies, from cliffs and on steep slopes facing the sun.

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

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Very 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 - Likely

Expected Size

2 - 3

Valid until: Mar 31st, 2016 4:00PM