Avalanche Forecast

Issued: Jan 9th, 2014 9:09AM

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

bcorrigan, Avalanche Canada

Kootenay Boundary.

Moderate to heavy precipitation combined with rising temps and high winds will drive the danger ratings for the next few days.

Summary

Confidence

Fair - Intensity of incoming weather systems is uncertain

Weather Forecast

Friday: 10 to 15 cm at upper elevations on Friday . Moderate to strong westerly winds for the day. Freezing levels are forecast to rise to 1000 m.Saturday: Increased precipitation, with up to 20 cm as a Pacific frontal system moves through the area. Freezing levels may rise to 1300 meters during the storm with strong SW winds.Sunday: Freezing level returns to 700 M in the wake of the Pacific frontal system, leaving another 10 cm in the forecast area. Strong winds persist.

Avalanche Summary

Surface sluffing only in recent reports.

Snowpack Summary

Moderate to heavy amounts of snow forecast for the weekend with strong SW winds will create wind slabs at tree line and above. Sluffing may occur in steep terrain and could easily run on surface hoar in sheltered alpine areas and below treeline. This surface hoar layer is sitting on a sun crust on S facing aspects in some locations. The persistent weak layers (PWL) are a concern to avalanche professionals as they have been producing sudden planar results and show good propagation potential when tested. The end of November facet/crust or surface hoar layer down 80 cm (or 40 cm where snowpack is very thin) and the depth hoar or basal facetting are the most worrisome layers. Presently, they do not seem reactive to skier triggering but this situation may change with additional loading from the incoming storm, rising temperatures, and strong wind.

Problems

Wind Slabs

High winds, rising temperatures and large amounts of precipitation in the forecast are adding up to a dangerous scenario for the next few days.

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 4

Storm Slabs

The recent snow may now be hiding windslabs that were easily visible before the snow fell.>Minimize exposure during periods of heavy loading from new snow, wind.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

1 - 4

Persistent Slabs

Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar, facet/crust and depth hoar.>Dig down to find and test weak layers before committing to a line.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 5

Valid until: Jan 10th, 2014 2:00PM