Avalanche Forecast

Issued: Dec 13th, 2018 4:26PM

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

jfloyer, Avalanche Canada

South Rockies.

Warming on Friday may have an adverse effect on snow stability, particularly on slopes that face the sun.

Summary

Confidence

Moderate - Freezing levels are uncertain on Friday

Weather Forecast

THURSDAY NIGHT: Light snow, 2 cm or so.FRIDAY: Sunny. Strong southwesterly winds. Freezing level around 1800 m. Light snow Friday night.SATURDAY: A mix of sun and cloud. Winds becoming light to moderate southwesterly. Freezing level around 900 m.SUNDAY: Flurries. Freezing level rising to around 1800 m. Moderate or strong southwesterly winds.

Avalanche Summary

No new avalanches have been reported in the region, but rugged travel conditions at lower elevations have lately been discouraging travel in the alpine, where the bulk of our current avalanche danger resides.

Snowpack Summary

About 20-25 cm of new snow has buried previous snow surfaces that ranged from soft power to hard wind slab and sun crust. Strong winds have likely been aggressively forming storm slabs and wind slabs with the new snow at higher elevations.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

Recent strong winds and new snow have set up wind slabs in many exposed alpine and treeline areas. Warming on Friday could have a destabilizing effect on these slabs.

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

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 around thick 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 14th, 2018 2:00PM