Avalanche Forecast

Issued: Mar 22nd, 2017 4:01PM

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

grant statham, Parks Canada

Banff Yoho Kootenay.

Although just over the peak of the avalanche cycle, we continue to see large avalanches running. The CONSIDERABLE danger rating below treeline exists due to the potential to be hit from above. Avalanches have been running to the valley bottom.

Summary

Weather Forecast

Southwest flow continues with flurries expected on Wednesday night, possible accumulations of 3-5 cm by Thursday. The temperatures will fall slightly on Thursday, but expect freezing levels to reach about 1500 meters and treeline temperature from -5 to -8. Winds will remain moderate from the southwest.

Snowpack Summary

100cm of dense, rounded snow comprises the upper half of the snowpack and sits on a very weak base of depth hoar. This unstable structure produces consistent, sudden collapse test results in the depth hoar layer approximately 60cm from ground. Two shears persist near the surface down 15 and 35cm indicating lingering instability in the storm snow.

Avalanche Summary

Report of big avalanche activity on the Bow Hut approach today. Fresh size 2 avalanche over the trail, and a very large (estimated size 3.5) deep slab from the Vulture Glacier ran over the Bow Hut headwall and covered the trail through the moraines. These are our only reports from today, but they indicate that large avalanches remain very likely.

Confidence

Problems

Deep Persistent Slabs

Large avalanches continue to run to the valley bottoms and cross popular trails. We show this problem as being below treeline not because you can trigger an avalanche, but because you can be hit by one from above. Watch out for overhead hazard!

Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

2 - 4

Wind Slabs

Wind loading was occurring through the day on Wednesday, and we expect fresh windslabs to be forming at higher elevations. Some speculate that today's wind loading was the trigger for a very large avalanche near Bow Hut.

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

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

2 - 3

Valid until: Mar 23rd, 2017 4:00PM