Avalanche Forecast

Archived

Dec 1st, 2021–Dec 2nd, 2021

Alpine

Natural and human triggered avalanches likely.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Regions

Jasper.

Maligne Lake Road and the Icefields Parkways are both currently closed. The Icefields Parkway could open from Jasper to Parker Ridge late Thursday morning. Check Alberta 511 for updates. This new snow will take time to settle so keep it conservative.

Weather Forecast

Thursday: A mix of sun and cloud.

Alpine temperature: High -9 C.

Ridge wind west: 20 km/h gusting to 50 km/h.

Freezing level at valley bottom.

Friday: Cloudy with sunny periods and isolated flurries.

Precipitation: Trace.

Alpine temperature: Low -16 C, High -13 C.

Mostly light ridge wind occasionally gusting to 35 km/h.

Freezing level at valley bottom.

Snowpack Summary

About 30 cm of storm snow fell in the last 24hrs in the Parker Ridge area. About 20cm of new snow around Maligne Lake. Freezing level is about 2100m with the snow line around 1200m. The mid-pack is around 80cm thick above a thin crust near the ground in some locations. Snowpack is shrinking rapidly at lower elevations.

Avalanche Summary

Multiple, natural wet loose avalanches up to Size 2 observed on the Icefields Parkway early in the storm. We can expect more have run since the storm started.

Confidence

Due to the number and quality of field observations

Problems

Storm Slabs

Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.

Deep Persistent Slabs

Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.