Avalanche Forecast

Issued: Feb 23rd, 2016 4:00PM

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

ian jackson, Parks Canada

Banff Yoho Kootenay.

Natural avalanche activity is tapering with the stable weather pattern. However, we have seen many large avalanches triggered in the last week with minimal inputs. This shows how touchy the current snowpack is. Stick to conservative terrain right now

Summary

Weather Forecast

A very strong ridge is moving into the region bringing clear skies and light NW winds. Temperatures will remain cool but the sun effect will be strong. This ridge is expected to remain in place for most of the week. We will see good overnight freezes on Tues and Wed PM with less of a freeze and warmer temperatures on Thursday and Friday.

Snowpack Summary

Sun crusts on solar aspects. Recent wind slabs and cornice growth in the alpine with 30-50 cm of snow in the last week. A 50-100 cm slab overlies the January 6 persistent weak layer of surface hoar, facets and sun crust which has had lots of avalanche activity on it in the last week. The lower snowpack is facetted and weak in thin snow pack areas.

Avalanche Summary

A size 2.5 avalanche ran on an east aspect alpine feature near Sunshine with the first rays of sun this morning. Otherwise, natural activity is tapering, but conditions remain prime for human triggering. For example, on Monday a skier was caught and partially buried in a size 2 slab triggered on a west aspect of Richardson's Ridge at Lake Louise.

Confidence

Freezing levels are uncertain on Friday

Problems

Persistent Slabs

50-100 cm of snow overlies the Jan 6th layer of surface hoar, facets and sun crust. Numerous avalanches have been triggered on this layer in the last week. In thin snow pack areas, some of these avalanches have stepped down to the ground.

Avoid paths that have not avalanched recently.Use conservative route selection, choose moderate angled and supported terrain with low consequence.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

2 - 3

Wind Slabs

Be wary of cross loaded features and the lees of ridges where recent moderate to strong W winds have formed wind slabs and developed fragile cornices. Recent wind slab avalanches have also stepped down to the persistent weak layer and the ground.

If triggered the wind slabs may step down to deeper layers resulting in large avalanches.Use caution in lee areas. Recent wind loading has created wind slabs.

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

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

1 - 2

Valid until: Feb 24th, 2016 4:00PM