Avalanche Forecast

Issued: Dec 27th, 2017 4:39PM

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

Avalanche Canada mbender, Avalanche Canada

The forecast calls for a dusting of low density new snow throughout the day on Thursday.

Summary

Confidence

Moderate - Forecast snowfall amounts are uncertain on Thursday

Weather Forecast

THURSDAY: Flurries, accumulation 5-10cm / Wind light south / Alpine temperature -10 FRIDAY: Isolated flurries and some sunny breaks / Wind light southeast / Alpine temperature -10 SATURDAY: Mix of sun and cloud / Wind light west / Alpine temperature -11

Avalanche Summary

Recent reports show continued observations of wind slabs releasing to Size 1 with skier traffic and ski cutting, primarily on south aspects in the alpine. Additional observations show numerous human triggered and natural loose dry avalanches to size 1 in steep, sheltered terrain. 

Snowpack Summary

Last week's storm brought 40-60cm of new snow to the region. Predominantly northerly winds have since redistributed this storm snow into wind slabs at higher elevations. In sheltered ares cold temperatures have largely prevented this snow from consolidating into a slab. The storm snow lies over a variety of old surfaces, including surface hoar (weak, feather-like crystals), sun crust, and sugary facets. The bond at this old snow interface is of critical importance in areas where the overlying snow has consolidated into a slab. The most concerning areas are those that saw pronounced surface hoar development before the storm, such as sheltered open areas at and below treeline or sheltered northerly aspects in the alpine. Recent snowpack tests show wide ranging reactivity at this interface but suggest that it may be most reactive on northerly aspects.A rain crust that formed in late November is now buried 80-110cm deep. Recent evidence suggests it may be reactive in steep, variably loaded terrain features in the alpine.

Problems

Wind Slabs

An icon showing Wind Slabs
Shifting winds have created wind slabs on a variety of aspects.
Use ridges or ribs to avoid pockets of wind loaded snow.Be aware of highly variable recent wind loading patterns.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Persistent Slabs

An icon showing Persistent Slabs
A weak layer of surface hoar buried 30-50 cm deep has potential to be reactive in areas where the overlying snow has settled into a cohesive slab.
Watch for signs of slab formation, such as whumpfing and shooting cracksApproach steep open slopes cautiously at and below treeline where buried surface hoar may exist.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Valid until: Dec 28th, 2017 2:00PM