Avalanche Forecast

Issued: Mar 28th, 2017 4:00PM

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

aaron beardmore, Parks Canada

Banff Yoho Kootenay.

Forecasters experienced a significant whumphf near Dolomite Pass today. A high degree of uncertainty still exists with the weak snowpack.

Summary

Weather Forecast

Up to 15cm of new snow and strong west wind is expected at high elevations over the next 48 hours. Temperatures near 2000m should remain at or below freezing. A clearing trend is emerging on the weather models for Friday.

Snowpack Summary

10 cm of snow sits over a solid 100cm+ slab which rests precariously over the weak basal facets at treeline and above. Tests produce consistent sudden collapse results in the facets, and this will not become stronger soon. The surface snow is of a mix of soft snow in the shade, melt-freeze snow below treeline, and sun crust on sun exposed slopes.

Avalanche Summary

Yesterday a size 3 avalanche was reported on the 'Onion Skin' near Bow Hut. A cornice dropped onto a slope which triggered the slide. It was reported that it ran for 800m. Additionally, forecasters experienced a significant whumphf near Dolomite Pass today. A high degree of uncertainty still exists.

Confidence

Timing, track, or intensity of incoming weather system is uncertain on Wednesday

Problems

Deep Persistent Slabs

Natural activity has decreased, but the snowpack has a weak base and remains quite suspect. Continue to approach avalanche terrain with suspicion and avoid most large slopes steep enough to slide. Human triggering remains likely in specific areas.

Be wary of slopes that did not previously avalanche.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

2 - 4

Cornices

There has been an increasing frequency of cornice failures this past week. Be wary of this as we transition into spring (cornice season). They are a hazard underfoot on ridge crests, and from overhead if you travel below one. GIve them a wide berth.

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

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 3

Loose Dry

New snow and strong West wind will create soft wind slabs in the alpine. The touchiness of the windslabs is uncertain as of Tuesday afternoon.

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

Elevations: Alpine.

Likelihood

Possible - Likely

Expected Size

1 - 2

Valid until: Mar 29th, 2017 4:00PM