Avalanche Forecast

Issued: Nov 27th, 2017 4:00PM

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

aaron beardmore, Parks Canada

Banff Yoho Kootenay.

There is still much uncertainty with the Oct 31 persistent weak layer. Conservative route choices are still suggested.

Summary

Weather Forecast

We are expecting precipitation starting at noon on Tuesday and accumulations of approximately 20cm by end of day Thursday. Luckily, the freezing level is expected to stay below surface and we will see this as snow. Wind will continue in the moderate range from the S-SW.

Snowpack Summary

Continued strong winds have created wind-slabs in lee areas in the alpine and have extended down to some tree line areas. The recent Nov 23 crust is located ~30cm below surface and is producing moderated snowpack test results. The main weakness in the snowpack remains the weak facets associated with the Oct 31 crust now buried ~70cm at treeline.

Avalanche Summary

One audible avalanche was heard by forecasters today near Crowfoot Glades. Likely it came from the cliffs high above. A surprising lack of activity was observed today after last nights warm temperatures and heavy precipitation.

Confidence

Forecast snowfall amounts are uncertain on Thursday

Problems

Persistent Slabs

Additional snow load and wind is adding volume on top of the Oct 31 crust. This layer remains active as evidenced by recent avalanches (Lake Louise yesterday) and snow pack tests in the hard range today at Crowfoot Glades.

Use conservative route selection, choose moderate angled and supported terrain with low consequence.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Wind Slabs

Fresh snow and moderate to strong winds have created fresh wind-slabs in the alpine in lee areas.

Use caution in lee areas. Recent wind loading has created wind slabs.

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

Elevations: Alpine.

Likelihood

Possible - Likely

Expected Size

1 - 2

Valid until: Nov 28th, 2017 4:00PM