Avalanche Forecast

Issued: Nov 24th, 2017 8:06AM

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

andrew jones, Parks Canada

Glacier.

Expect poor snow quality due to massive amounts of recent rainfall.

Summary

Weather Forecast

After a warm and rainy storm, we will see a return to winter. For today, SW moderate winds gusting to 50km/h, 4cm of snow and freezing levels below 1300m. Expect cooler temperatures and scattered flurries heading into the weekend. A frontal system arrives early Sunday morning with warming temperatures and up to 35cm of snow.

Snowpack Summary

65mm of rain has fallen at Rogers Pass over the last 3 days. The added moisture has dramatically changed the snow quality from early season powder to a saturated upper snowpack capped by a thin surface crust. In the alpine, extreme southerly winds have created a wind slab problem on lee features. October 31 crust is buried 100cm at treeline.

Avalanche Summary

A widespread nature avalanche cycle occurred yesterday with the ongoing rainfall and strong winds. Several large size 3.0 wet slab avalanches were observed in the highway corridor. Artillery avalanche control produced large avalanches in the east end of Rogers Pass. A size 3.0 natural avalanche was observed on the Thorington route of Mt Jupiter.

Confidence

Problems

Wind Slabs

Extreme southerly winds accompanied yesterday's storm and created reactive wind slabs. This problem is specific to the alpine due to intense rainfall and warmer temps at lower elevations during the storm.

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

2 - 3

Persistent Slabs

This layer was awakened by heavy loading during the last storm. Although natural avalanche activity has subsided, this crust remains a concern due to its persistent nature in the snowpack. Human triggering is certainly possible.

Caution around convexities or areas with a thin or variable snowpack.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

2 - 4

Valid until: Nov 25th, 2017 8:00AM