Avalanche Forecast

Issued: Dec 7th, 2014 4:22PM

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

patrick jerome, Parks Canada

Banff Yoho Kootenay.

The structure of this early season snowpack is poor and will remain very sensitive to snow riders for the next several weeks to come. Conservative terrain selection and minimizing your exposure to a nasty ride is the name of the game these days. PJ

Summary

Weather Forecast

The forecast temperature going into next week will be another warming trend with freezing levels rising to Treeline elevation by Tuesday and into Wednesday. Accompanying this Southwest flow will bring light precipitation and strong winds in the Alpine.

Snowpack Summary

Warmer daytime temperatures this weekend are promoting settlement of the upper snowpack and creating more of a slab over the basal facets especially in wind affected areas. The lower half of the snowpack is poorly structured, with facets (Nov 24th) below the recent storm snow, thin crusts (Nov 6th) below this, and then depth hoar near the ground.

Avalanche Summary

Skier triggering is still high in likelihood particularly coupled with the recent daytime warming. Two size 2 skier accidentals were triggered this afternoon just outside ski area boundaries around Sunshine and Lake Louise back country. This reaffirms the weak basal layers persist and remain prone to human triggering so very little has changed.

Confidence

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

Problems

Deep Persistent Slabs

The primary problem in the snowpack is the interface between the recent storm snow and the November 6th and 24th facet/crust interfaces. Owing to the delicate structure of these layers we expect this problem will persist for the foreseeable future.

Use conservative route selection, choose moderate angled and supported terrain with low consequence.Be aware of the potential for full depth avalanches due to deeply buried weak layers.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

2 - 3

Wind Slabs

Mild temperatures and westerly flow will cause wind slabs to develop in exposed areas at tree line and above. Watch for pockets of hard slab near ridge tops and on cross loaded features.

Be careful with wind loaded pockets while approaching and climbing ice routes.Watch for whumpfing, hollow sounds, and shooting cracks.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

2 - 2

Valid until: Dec 8th, 2014 4:00PM