Avalanche Forecast

Issued: Nov 25th, 2017 4:00PM

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

tim haggarty, Parks Canada

Banff Yoho Kootenay.

Another storm will reach the area Sunday afternoon. Caution is recommended at treeline and above as this new load tests the persistent weak layer.

Summary

Weather Forecast

Another system is forecast to arrive Sunday afternoon. The pattern of this storm will be much the same as the last however freezing levels look to be much lower at around 2000m. We expect up to 20mm to arrive with moderate SW winds as first the warm front passes followed by a cold front at around 9 pm.Â Further precip is expected through Tuesday.

Snowpack Summary

In the Alpine there has been significant amounts of both snow and wind in the last two weeks. Significant amounts of Precip came as rain below about 2500m on Thursday creating a new crust that has 5 to 10 cm over it. The main concern in the snowpack remains the weak facets associated with the Halloween crust in the mid to lower snowpack.

Avalanche Summary

Although natural avalanche activity has slowed with more settled weather in the last few days a few have been reported on the crust and facets at around the 2500m range to sz 2.5. A significant cornice failure was also reported by Sunshine Village.Â Explosive control continues to produce results on the facets /crust as well as a few wind slabs.

Confidence

Timing, track, or intensity of incoming weather system is uncertain on Sunday

Problems

Persistent Slabs

While the snow became soaked at lower elevations and has a thick refrozen surface crust, the new crust gets thin above 2400m and it is uncertain whether the deeper Halloween crust will continue to be reactive. A conservative approach is recommended.

Minimize exposure during periods of heavy loading from new snow and wind.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Wind Slabs

Given the amount of snow and wind that the alpine has seen in the last several days, a few reactive windslabs can likely still be found. Expect the incoming storm to create touchy new slabs as it passes.

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

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

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 2

Valid until: Nov 26th, 2017 4:00PM