Avalanche Forecast

Issued: Mar 7th, 2016 5:31PM

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

conrad janzen, Parks Canada

Banff Yoho Kootenay.

A couple close calls recently with avalanches failing on the mid-pack facets highlight the need to use caution in steep terrain. There is some great skiing to be had above treeline but stick to moderate angled terrain with low consequences.

Summary

Weather Forecast

A cooling trend is expected to continue over the next two days with light West winds and occasional light flurries. The freezing level is expected to be around the surface overnight, rising to 1600m during the day.

Snowpack Summary

5-10 cm of new snow Monday, becoming moist below 1700m. Buried sun crusts on solar aspects. Recent moderate West winds have formed wind slabs in lee areas of the alpine. A firm upper snow pack sits over a generally weak mid-pack of facets and depth hoar. In shallow areas snowpack tests results are typically collapses near the ground.

Avalanche Summary

Monday a skier accidental size 2.5 on the Collie Glacier, at 2600m, approaching the Richard and Louise Guy Hut from Mt Collie. The avalanche failed on the Jan 6th mid-pack facets and was triggered when crossing below a steep rocky slope in poor visibility. 2 partial burials with minor injuries. Sunday a skier accidental size 2.5 near Bow Summit.

Confidence

Due to the number and quality of field observations

Problems

Deep Persistent Slabs

The mid-pack facets remain weak, especially in thin or rocky areas. Avoid steep or unsupported terrain, and watch for signs of instability such as whumphing and cracking. This weakness will be present for some time.

Be aware of thin areas that may propogate to deeper instabilites.Caution around convexities or areas with a thin or variable snowpack.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 3

Wind Slabs

Recent W winds and new snow have created wind slabs in leeward ares near ridge crests. Pay attention to the snow surface conditions while touring - you can usually detect wind slabs easily and avoid these spots.

If triggered the storm/wind slabs may step down to deeper layers resulting in large avalanches.Be careful with wind loaded pockets, especially near ridge crests and roll-overs.

Aspects: North, North East, East.

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 2

Loose Wet

Daytime heating may cause loose wet avalanches at lower elevations. This activity will increase when the sun comes out during the next few days. Minimize your exposure to steep solar aspects when things heat up.

Travel early before the heat of the day, and avoid big slopes in the afternoon.

Aspects: North, North East, East.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Valid until: Mar 8th, 2016 4:00PM