Archived

Avalanche Forecast

Jan 3rd, 2017–Jan 4th, 2017

Alpine

2: Moderate

The avalanche danger rating in the alpine will be moderate

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Alpine

2: Moderate

The avalanche danger rating in the alpine will be moderate

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Alpine

2: Moderate

The avalanche danger rating in the alpine will be moderate

Treeline

1: Low

The avalanche danger rating at treeline will be low

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Regions: Kootenay Boundary.

Cold north winds have been blowing. Be on the watch for wind slabs, particularly on southerly aspects

Confidence

Moderate - Due to the number of field observations

Weather Forecast

The arctic outbreak continues with cold temperatures and no snow until Sunday at the earliest. WEDNESDAY: Dry and sunny. Winds light north/northeasterly 5-15 km/h. Temperatures between -18 and -26 Celcius!THURSDAY: A mix of sun and cloud. Wind light west. Temperatures between -13 and -20 Celcius. No precipitation. FRIDAY: Cloudy with sunny periods. Wind becoming southwesterly 5-15 km/h. Temperatures between -12 and -20 Celcius. No precipitation.

Avalanche Summary

We've had reports of several natural and skier-triggered windslabs (Size 1.5-2) yesterday in the backcountry near Nelson. Aspects were southwest through north at treeline and in the alpine.

Snowpack Summary

This region saw 30-60 cm new snow during last week's storms (with more in the eastern areas and less in the west). The new snow sits over a weak layer buried on Boxing Day that was initially reactive but now appears to have gained strength. Recent winds switched from mainly southwesterly to northerly, "reverse loading" areas and causing windslabs. Slightly lower in the snowpack is an interface buried mid-December, now down 40-100 cm. This layer appears to be well bonded in many parts of the region but was reactive for a while last week west of Trail and Castlegar where preserved surface hoar was thought to be responsible for four small (but surprising) skier trigger avalanches. It will be important to continue to monitor this layer for further signs of reactivity.

Avalanche Problems

Wind Slabs

Wind slabs have been forming on mainly southwest to north aspects behind exposed terrain features. Slabs found on south aspect slopes could become more unstable when the sun is out.

Use ridges or ribs to avoid pockets of wind loaded snow.Use caution in lee areas. Recent wind loading has created wind slabs.

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

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1 - 2