Avalanche Forecast

Issued: Dec 11th, 2018 5:06PM

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

cgarritty, Avalanche Canada

South Rockies.

A bit more snow and a lot more wind are in the forecast. Finding a spot beneath the wind effect but above the snowline will be difficult.

Summary

Confidence

Moderate - Forecast snowfall amounts are uncertain

Weather Forecast

Tuesday night: Cloudy with flurries bringing 5-10 cm of new snow. Moderate to strong southwest winds.Wednesday: A mix of sun and cloud with easing isolated flurries and a trace of new snow. Moderate to strong northwest winds. Alpine high temperatures around -9.Thursday: Mainly cloudy with another round of flurries bringing about 5 cm of new snow. Strong to extreme southwest winds. Alpine high temperatures increasing to around -3 with freezing levels continuing to rise from 1500 to 2000 metres overnight.Friday: A mix of sun and cloud. Strong southwest winds. Alpine high temperatures around 0 to +1 as freezing levels jump to a possible 2400 metres.

Avalanche Summary

No new avalanches have been reported in the region. Small wind slabs have been reported in neighboring regions.

Snowpack Summary

Light new snow amounts have begun to bury previous surfaces that ranged from soft power to hard wind slab, and sun crust. The new snow is also burying Isolated pockets of stiff wind slab that likely exist on leeward slopes. Beneath the new snow and old surface, the snowpack has a thin, weak structure, with the bottom half of the snowpack composed of weak facets and crusts. This basal layer has not been active, but terrain features like smooth alpine bowls with variable snowpack depths are still suspect given this snowpack structure. Currently only 30-90 cm of snow can be found in alpine areas and much less at lower elevations

Problems

Wind Slabs

Forecast strong winds and light snowfall are expected to layer thin but touchy new wind slabs over the last round of stiffer, older slabs. Wind slab releases have the potential to produce large avalanches if they step down to the weak basal snowpack.

Use ridges or ribs to avoid pockets of wind loaded snow.Be alert to conditions that change with elevation, aspect and exposure to wind.If triggered the wind slabs may step down to deeper layers resulting in large avalanches.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Deep Persistent Slabs

The weak snow in the lower snowpack could produce large avalanches. Be cautions in areas where the surface snow has formed a cohesive slab, such as wind deposits.

Avoid shallow, rocky areas where the snowpack transitions from thick to thin.Be especially cautious as you transition into wind affected terrain.Back off if you encounter signs of instability like whumphing, shooting cracks or recent avalanches.

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Unlikely - Possible

Expected Size

1 - 2

Valid until: Dec 12th, 2018 2:00PM