Avalanche Forecast

Issued: Dec 9th, 2017 3:58PM

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

mconlan, Avalanche Canada

Kootenay Boundary.

Shady slopes offer the best snow. Isolated wind slabs may exist at high elevations.

Summary

Confidence

High - The weather pattern is stable

Weather Forecast

SUNDAY: Mostly sunny with valley clouds, moderate northwesterly winds, freezing level around 3200 m with below-freezing temperatures in the valleys.MONDAY: Sunny with valley clouds, light southwesterly winds, freezing level around 3500 m with below-freezing temperatures in the valleys.TUESDAY: Partly sunny with valley clouds, light to moderate westerly winds, freezing level dropping to 2500 m with below-freezing temperatures in the valleys.

Avalanche Summary

Small wind slabs were released on Friday by a skier and explosives in alpine lee features. Small loose wet avalanches were observed on steep south-facing slopes on Thursday.

Snowpack Summary

Moderate to strong winds from the west and northwest at higher elevations may be forming new wind slabs in southerly and easterly lee features. These wind slabs may sit above lingering wind slabs from the past week. The warm air temperatures and clear skies from the past few days have caused melting of the surface snow on south-facing slopes. Crusts may form overnight but should melt quickly in the mornings if clear skies prevail. Surface hoar to 30 mm has been observed along with near-surface faceting in the top 20 cm of the snowpack. Beneath this, the warm weather has settled the snowpack and may be improving the bond to the 30-50 cm deep rain crust from late November, but there are still limited observations of this layer. On ridges, cornices may be weakening with the warm air temperatures.

Problems

Wind Slabs

Increased westerly winds may have produced new wind slabs, particularly in alpine terrain behind ridges. These slabs may sit on lingering slabs from earlier in the week. Be cautious of firm snow when entering lee features.

Avoid wind-loaded pockets near ridges.If triggered, wind slabs may step down to deeper layers resulting in large avalanches.

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 2

Loose Wet

Warm air temperatures and clear skies have produced spring-like conditions on steep solar aspects. Loose wet avalanches may begin small but could step down to deeper crust layers.

Loose wet avalanches may trigger deeper layers resulting in large avalanches.Use caution above cliffs and terrain traps, where small avalanches may have severe consequences.Avoid sunny slopes when the solar radiation is strong, especially if the snow is moist or wet.

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

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

1 - 2

Valid until: Dec 10th, 2017 2:00PM