Avalanche Forecast

Issued: Nov 27th, 2015 4:07PM

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

Conrad Janzen, Parks Canada

Banff Yoho Kootenay.

The temperature inversion continues with very warm alpine temperatures on Saturday and Sunday. Ice climbers in particular should expect solar triggered snowballing and sluffing out of steep rocky South facing terrain during the heat of the day.

Summary

Weather Forecast

Clear conditions with light winds and very warm alpine temperatures are forecast for Saturday with alpine temperatures remaining near freezing for Saturday night. In sheltered sunny locations temperatures will get well above freezing during the middle of the day. A temperature inversion will keep the valley bottoms cool.

Snowpack Summary

Sun crust forming on sheltered solar aspects. Below treeline the snowpack has set up well and is slowly facetting. In open areas at tree line and above there are numerous wind slabs of varying depth. Isolated wind slabs over facets typical of the Rockies can still be expected in thin areas.

Avalanche Summary

Some small solar triggered sluffs to size 1 observed on Friday. One older size 3 natural avalanche was also observed on the White Pyramid Glacier. This appears to have slid during the last major wind event a few days ago. In places it stepped down to glacier ice showing that on high North aspects there can be a basal weak layer to keep in mind.

Confidence

Due to the number of field observations

Problems

Loose Wet

With alpine temperatures only dropping a little below freezing overnight, we expect to see an increase in solar triggered sluffing on Saturday and Sunday.

Avoid ice climbs exposed to steep rocky terrain on solar aspects during the middle of the day.

Aspects: North, North East, East.

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 2

Wind Slabs

Small wind slabs are possible in isolated locations, perhaps providing a surprise during otherwise good conditions. The main concern is for terrain traps (above cliffs, gullies) where small avalanches have bigger consequences.

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

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Unlikely - Possible

Expected Size

1 - 2

Valid until: Nov 28th, 2015 4:00PM