Avalanche Forecast

Issued: Dec 5th, 2018 4:30PM

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

cgarritty, Avalanche Canada

Kootenay Boundary.

The strength of the snowpack is slowly improving, but it's still a good plan to keep your guard up around steeper, sheltered slopes and rolls at treeline and above.

Summary

Confidence

Moderate -

Weather Forecast

Wednesday night: Mainly clear with some low level cloud. Light variable winds.Thursday: A mix of sun and low level cloud. Light northwest winds. Alpine high temperatures around -10.Friday: Mainly sunny with some low level cloud. Light southwest winds. Alpine high temperatures around -6, cooler at lower elevations due to an alpine temperature inversion.Saturday: Mainly cloudy. Light southwest winds. Alpine high temperatures around -6 with the temperature inversion mostly dissipated.

Avalanche Summary

No avalanches have been reported since November 24. Please post your observations to the Mountain Information Network here.

Snowpack Summary

Days of cold temperatures have been gradually transforming about 30 cm of aging storm snow left on the surface from storms and flurries over the past couple of weeks into a layer of faceted (sugary, cohesionless) snow. At treeline, the total height of snow is between about 100 and 140 cm. At 50 to 70 cm below the surface, there is a closely stacked pair of buried persistent weak layers. The upper layer consists of surface hoar (feathery crystals) in most places, but may present as a sun crust on steep south facing slopes. The deeper layer features similar surface hoar distribution over a more widespread temperature crust. These layers have shown ongoing but variable reactivity in snowpack tests in the past week. Both surface hoar layers are thought to be widespread at treeline and may also extend into sheltered alpine features.At the base of the snowpack is a thick melt-freeze crust that formed near the end of October. Observations of reactivity at this crust have been limited, but it has acted as the failure plane in several recent large avalanches in the neighbouring South Columbias.

Problems

Persistent Slabs

Storm snow from the past couple of weeks is consolidating into a slab that rests on a persistent weak layer 40 to 80 cm below the surface. This layer seems to be most prevalent at treeline, but likely extends into the alpine in sheltered terrain.

Avoid steeper open slopes and convex rolls at treeline where buried surface hoar may be preserved.Back off if you encounter signs of instability such as whumpfing, cracking, or recent avalanches.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

1 - 2

Valid until: Dec 6th, 2018 2:00PM