Avalanche Forecast

Issued: Nov 26th, 2017 4:40PM

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

snow safety, Parks Canada

Banff Yoho Kootenay.

Avalanches are continuing to run on the Halloween persistent weak layer. Conservative route choices are in order.

Summary

Weather Forecast

There will be a cooling trend with freezing levels lowering to around 1200 m on Monday. Light snow expected throughout the day on Monday with accumulations at treeline up to 10 cm. Continued unsettled weather on Tuesday.

Snowpack Summary

Recent fresh snow and strong south and south west winds will have created fresh wind-slabs in the high alpine. At tree-line and below a warm and rain soaked upper pack sits over the Halloween crust which is 20-40 cm above the ground. The main weakness in the snowpack remains the weak facets associated with the Halloween crust.

Avalanche Summary

Warm temperatures and rain below 1900 m have weakened the snow-pack. Lake Louise Ski Hill triggered a bunch of avalanches up to size 2.5 with explosives on Sunday and there was a boarder triggered size 2.5 avalanche in Westbowl. Avalanches were running on the Halloween layer near the base of the snow-pack.

Confidence

Problems

Persistent Slabs

New snow and rain below 1900 m have added extra weight to the snowpack. The Halloween persistent weak layer remains active as indicated by fresh avalanche activity reported at Lake Louise (see avalanche details).

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

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 3

Wind Slabs

Fresh snow and mod to strong SW winds will have created fresh wind-slabs in the alpine.

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 27th, 2017 4:00PM