Avalanche Forecast

Issued: Dec 27th, 2017 4:42PM

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.

mbender, Avalanche Canada

Cariboos.

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

Summary

Confidence

Moderate - Forecast snowfall amounts are uncertain on Thursday

Weather Forecast

THURSDAY: Flurries, accumulation 5-10cm / Wind light east / Alpine temperature -16 FRIDAY: Mostly sunny / Wind light northeast / Alpine temperature -18 SATURDAY: Mix of sun and cloud / Wind light west / Alpine temperature -12

Avalanche Summary

No new avalanches have been reported in the region. In addition to lingering wind slabs at higher elevations, persistent slab avalanche danger remains a concern in areas where the last week's storm snow has consolidated into a slab above the December 15 interface. Please submit your observations to the Mountain Information Network (MIN).

Snowpack Summary

Last week's storm brought 20-40cm of new snow to the region. Predominantly northwest winds since the storm redistributed loose snow at the surface into wind slabs on a variety of aspects at higher elevations while cold temperatures inhibited slab formation elsewhere. The cold has also worked to break down the cohesion and reactivity of older wind slabs. The storm snow lies over a variety of old surfaces, including large surface hoar (weak, feather-like crystals), crusts formed by sun or wind, and sugary facets. The bond at this old snow interface is of the greatest importance in areas where the overlying snow has consolidated into a slab. The most concerning areas areas are those that saw pronounced surface hoar development in advance of the storm, such as sheltered areas at and below tree line.A crust which was formed by rain in late November is another major feature in the snowpack and is down approximately 70-100cm at tree line elevations. This interface has shown some signs of reactivity limited to steep, variably loaded alpine features in adjacent regions.

Problems

Wind Slabs

Recent shifting winds have been redistributing loose snow into wind slabs on a variety of aspects.

Use ridges or ribs to avoid pockets of wind loaded snow.Be aware of recent variable 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 20-40 cm deep has potential to be reactive where the overlying snow has settled into a cohesive slab.

Watch for signs of slab formation at lower elevations, such as whumphing or shooting cracks.Buried surface hoar is more likely to be preserved in sheltered openings at and below tree line.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

1 - 2

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