Avalanche Forecast

Issued: Apr 3rd, 2018 4:19PM

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

Lisa Paulson, Parks Canada

Banff Yoho Kootenay.

The cooler temps are maintaining the fantastic ski quality. Use caution on solar aspects where the recent snow is reactive to skier triggering on buried crusts in specific locations.

Summary

Weather Forecast

Unseasonably cold temperatures remain (below zero) in the Valley bottoms for a few days yet. The overnight ridge temperature will stay in the -15 range until Thursday. Cloud cover and light amounts of precip are expected to continue Wed & Thurs. The wind will be SW and increase to moderate as snow squalls pass through the region on Wednesday.

Snowpack Summary

Last weeks storm brought 15-40cm with moderate S and W winds creating wind slabs in the alpine and into exposed areas at treeline. The March 15 suncrust is down 25-50cm on south-east through west aspects and has been sensitive to skier triggering over the last few days. The mid- pack land basal layers have been dormant for the past while.

Avalanche Summary

Skier remote size 1.5 & 2 just outside Lake Louise ski area boundary on East to SE aspects yesterday and today. Both avalanches failed on a buried suncrust down 20-40 cm and occurred in the afternoon.

Confidence

Problems

Wind Slabs

Expect to encounter windslabs on all aspects at treeline and higher. They range from 20 to 40cm thick. On solar aspects, where the Mar 15 crust exists, potential remains for these wind slabs to be touchier than polar aspects.

Use caution in lee areas. Recent wind loading have created wind slabs.Watch for surface cracking and stiffer surface layers of snow.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Persistent Slabs

Dig down to test the bond between the recent storm snow and the Mar 15 crust. Forecasters suspect faceting on the Mar 15 crust due to recent cold temps. Seems most sensitive with daytime heating allowing the surface snow to propagate as a soft slab.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Valid until: Apr 4th, 2018 4:00PM