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Avalanche Forecast

Dec 27th, 2017–Dec 28th, 2017
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
1: Low
The avalanche danger rating below treeline will be low
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
1: Low
The avalanche danger rating below treeline will be low
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
1: Low
The avalanche danger rating below treeline will be low

Regions: North Columbia.

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

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.

Avalanche Problems

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

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