Avalanche Forecast

Issued: Dec 5th, 2017 4:22PM

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

mgrist, Avalanche Canada

Kootenay Boundary.

The lure of powder slopes and sunny skies will be strong as the weather clears. Take a cautious approach towards more aggressive terrain - especially steep, wind-affected terrain.

Summary

Confidence

Moderate - Due to the number of field observations

Weather Forecast

We're looking at fine weather for the foreseeable future. Temperatures will warm significantly starting Wednesday afternoon. Wednesday: Sunny. Light northerly winds. Freezing levels rising to 2500m by the end of the day.Thursday: Sunny and warm. Freezing levels around 3300 m. Light northwesterly winds.Friday: Sunny and warm. Freezing levels 3200m. Light northerly winds.

Avalanche Summary

On Tuesday we had reports of natural Size 2 to 2.5 wind slab avalanches in the alpine, as a result of the 'reverse loading' pattern caused by north west winds. On Sunday we had reports of natural and skier triggered storm slab avalanches to Size 2 near Nelson. See here for the MIN report. On Saturday a Size 1 skier-triggered avalanche was reported on an unsupported steep gully feature near Nelson. See here for the MIN report. We currently have very limited observations in this region. Please submit your observations to the Mountain Information Network (MIN).

Snowpack Summary

30 - 50cm of new snow has fallen in the past week. At higher elevations, north west winds redistributed the snow, forming wind slabs on down wind (lee) features.Below the recent storm snow you'll likely find a couple of widespread crusts (2 to 5 cm thick) which formed as a result of late November's rain. The depth of the snowpack varies greatly with elevation. Recent reports suggest the average depth is 100-170cm in the alpine, 50-100cm at tree line, and decreasing rapidly below tree line where the primary hazards are rocks, stumps, and open creeks. We currently have very limited snowpack observations within this region and it is critical to supplement this information with your own observations.

Problems

Loose Wet

Conditions will be more like spring than winter starting Wednesday. Surface snow layers can become weak when hit by the sun. Minimize your exposure to terrain traps - even small sluffs can push you into dangerous terrain.

Use extra caution on sunny slopes or if the snow is moist or wet.Use caution above cliffs and terrain traps where small avalanches may have severe consequences.

Aspects: North, North East, East.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 2

Wind Slabs

The current pattern of wind loading in the alpine is NOT what we usually see - winds have been from the north west, creating wind slabs on south and east facing slopes.

Be careful with wind loaded pockets on downwind (south east facing) slopes.Be alert to changing snow conditions, especially where the snow firms up or sounds hollow.

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

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 3

Valid until: Dec 6th, 2017 2:00PM