Avalanche Forecast

Issued: Mar 26th, 2017 4:14PM

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

conrad janzen, Parks Canada

Banff Yoho Kootenay.

Very good skiing and travel conditions are present a higher elevations, but it makes sense to stick to conservative terrain choices with minimal overhead hazard. We are still getting fairly regular reports of large natural avalanches running far.

Summary

Weather Forecast

Increasing cloudiness with freezing levels up to 1800m and slightly warmer temperatures are forecast on Monday with daytime highs at valley bottom approaching 10 degrees and lows below freezing. Expect a few cm's of new snow in the alpine with Moderate SW winds.

Snowpack Summary

10-15cm 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. Some wind slabs present near alpine ridges, and sun crust on solar aspects. Below treeline a melt freeze cycle is developing, with the snowpack weakening in the PM.

Avalanche Summary

Natural activity has decreased over the last few days however avalanche reports continue to come in. A cornice triggered Na size 3 was observed on Fatigue Mountain Sunday, and reports of solar triggered avalanches up to size 3 East of our forecast area. It still appears to take only small inputs of sun, wind or precip to trigger natural events.

Confidence

Freezing levels are uncertain on Monday

Problems

Deep Persistent Slabs

Natural activity has decreased, but the snowpack has a weak base and is still very suspect right now. Any avalanche triggered on this deep facet layer will be large. Large avalanches initiating in the alpine have recently run to valley bottom.

Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.Be wary of slopes that did not previously avalanche.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

2 - 4

Wind Slabs

Wind transport continues near ridge crests in the alpine and the new growth on cornices appears to be quite fragile. Avoid areas with recent wind loading and terrain threatened by cornices.

Pay attention to overhead hazards like cornices which could easily trigger the deep persistent slab.If triggered the wind slabs may step down to deeper layers resulting in large avalanches.

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

Elevations: Alpine.

Likelihood

Possible

Expected Size

2 - 3

Loose Wet

Increased daytime temperatures will result in a deteriorating snowpack structure below tree line. Keep a close eye on temperatures changes throughout the day, and the strength of solar inputs on steep solar aspects.

Minimize exposure to steep, sun exposed slopes when the solar radiation is strong.Use extra caution on slopes if the snow is moist or wet.

Aspects: North, North East, East.

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 2

Valid until: Mar 27th, 2017 4:00PM