Avalanche Forecast

Issued: Dec 10th, 2017 4:01PM

The alpine rating is low, 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

MONDAY: Clear skies with valley clouds, light westerly winds, freezing level around 3600 m with below-freezing temperatures in the valleys.TUESDAY: Mostly clear skies with valley clouds, light to moderate westerly winds, freezing level dropping to 2500 m with below-freezing temperatures in the valleys.WEDNESDAY: Partly cloudy with valley clouds, light northwesterly winds, freezing level around 2500 m with below-freezing temperatures in the valleys.

Avalanche Summary

Small loose dry avalanches were observed from skier traffic in steep terrain on Saturday. 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 winds from the west and northwest may have formed wind slabs in southerly and easterly lee features. These may sit above lingering slabs from last week. The warm air temperatures and clear skies from the past few days have caused melting of the surface snow on south-facing slopes near treeline and above. Crusts may form overnight but should melt quickly in the mornings if clear skies prevail. Dry snow is generally found on shady slopes and below treeline, which may produce sluffing in steep terrain. Surface hoar to 30 mm has been observed along with near-surface faceting in the top 20 cm of the snowpack. Beneath this, the snowpack has settled and may be improving the bond to the 30-50 cm deep rain crust from late November. However, there are still limited observations of this crust layer. On ridges, cornices may be weakening with the warm air temperatures.

Problems

Wind Slabs

Increased winds may have produced wind slabs in lee features. These may sit on lingering slabs from last week.

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

Aspects: All aspects.

Elevations: Alpine, Treeline.

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.

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

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

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

1 - 2

Valid until: Dec 11th, 2017 2:00PM