Avalanche Forecast

Issued: Nov 19th, 2017 3:00PM

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

Alberta Parks jeremy.mackenzie, Alberta Parks

Windy and snowy conditions tonight will lead to natural avalanche activity on Monday. Human-triggering will increase to the "very likely" range. Cautious route selection is in order. An avalanche involvement occurred yesterday - see "Details" tab.

Summary

Confidence

Moderate - Intensity of incoming weather systems is uncertain

Weather Forecast

A snowy and windy night on Sunday is expected. Monday will be cloudy with sunny periods and isolated flurries. Alpine temperature should reach a high of -8 °C with ridge-top winds near 25km/h from the West. Tuesday and Wednesday will be snowy with possible accumulations up to 25cm.

Avalanche Summary

Visibility was limited today. One naturally triggered size 1.5 slab avalanche occurred in the past 24hrs on a steep E aspect at 2500m. This slab was approximately 20m wide, 40 cm deep and ran 100m. In addition, rescue crews responded to a serious avalanche involvement yesterday on Mt Arethusa. A party of 3 triggered a size 2.0 slab avalanche in steep Alpine terrain on a S aspect. This slide partially buried one person and fully buried another as the group boot-packed up a gully. The fully buried subject was successfully extricated by his companions, but suffered numerous serious traumatic injuries. Check out KCPS Facebook for photos.

Snowpack Summary

A few flurries today has not added much to the snowpack yet, but there will likely be more accumulation through the night with strong to extreme SW winds. Intense winds are the dominate part of the story, as wind slabs are already widespread at Treeline and Alpine elevations, and these will continue to build over the next 72hrs. These slabs are found on lee and cross-loaded features and are particularly prevalent in gullies features and immediately below ridge-crests. The Halloween crust is buried 40 to 60cm and has shown signs of facetting. Recent snowpack tests show a failure immediately underneath the crust, that will be something to watch in the weeks to come.

Problems

Wind Slabs

An icon showing Wind Slabs
Wind slabs are found on lee and cross-loaded features. Further slab development will occur through the night due to an intense storm that is moving through.
Avoid freshly wind loaded features.Be careful with wind loaded pockets while approaching and climbing ice routes.Avoid lee and cross-loaded terrain near ridge crests.

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

Elevations: Alpine, Treeline.

Likelihood

Likely - Very Likely

Expected Size

2 - 3

Valid until: Nov 20th, 2017 2:00PM