Archived

Avalanche Forecast

Feb 1st, 2018–Feb 2nd, 2018

Alpine

4: High

The avalanche danger rating in the alpine will be high

Treeline

4: High

The avalanche danger rating at treeline will be high

Below Treeline

3: Considerable

The avalanche danger rating below treeline will be considerable

Alpine

4: High

The avalanche danger rating in the alpine will be high

Treeline

4: High

The avalanche danger rating at treeline will be high

Below Treeline

4: High

The avalanche danger rating below treeline will be high

Alpine

3: Considerable

The avalanche danger rating in the alpine will be considerable

Treeline

3: Considerable

The avalanche danger rating at treeline will be considerable

Below Treeline

3: Considerable

The avalanche danger rating below treeline will be considerable

Regions: Little Yoho.

There's plenty of loose snow available for transport, and big winds are forecast for Friday and Saturday. This in conjunction with incoming snow will likely induce another avalanche cycle.

Weather Forecast

Fridays big story will be the forecasted alpine winds in the 70 - 90kmh range and rising temperatures in front of the next system. The Field area will see 10cm Friday and 30+cm by Saturday night. We expect another avalanche cycle given this forecast.

Snowpack Summary

40-80 cm of snow over the last seven days has overloaded 3 persistent weak layers of surface hoar and facets in the upper half of the snowpack: Jan 16 down 30-50cm; Jan 6 down 40-70cm; and Dec15 down 60-100+cm. A major avalanche cycle occurred Tuesday/Wednesday with avalanches running fall path on these layers and some stepping down even deeper.

Avalanche Summary

Natural activity has tapered slightly, but big results with explosives over the last few days to size 3.5 proves that these layers are prime for triggering. Some avalanches ran full path and put dust or debris on roads. Many slopes haven't slid yet, and any additional input (snow/wind/human) will overload the snowpack.

Confidence

Avalanche Problems

Persistent Slabs

Three weak layers exist in the upper snowpack: Jan 16, Jan 6, and Dec 15. All are a mix of sun crust, surface hoar and facets depending on your aspect and elevation. Destructive avalanches have occurred on these and will continue over the few days.

Watch for whumpfing, hollow sounds, shooting cracks or recent avalanches.Avoid all avalanche terrain.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely - Very Likely

Expected Size: 2 - 3.5

Wind Slabs

With plenty of loose snow around, incoming wind will form slabs quickly, adding to existing ones. The slabs are plump and ripe for triggering, and will likely step down to persistent weak layers.

If triggered the storm/wind slabs may step down to deeper layers resulting in large avalanches.Avoid all avalanche terrain.

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

Elevations: Alpine, Treeline.

Likelihood: Very Likely

Expected Size: 1 - 2.5