Archived

Avalanche Forecast

Feb 5th, 2016–Feb 6th, 2016

Alpine

4: High

The avalanche danger rating in the alpine will be high

Treeline

3: Considerable

The avalanche danger rating at treeline will be considerable

Below Treeline

2: Moderate

The avalanche danger rating below treeline will be moderate

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

2: Moderate

The avalanche danger rating below treeline will be moderate

Alpine

3: Considerable

The avalanche danger rating in the alpine will be considerable

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

2: Moderate

The avalanche danger rating below treeline will be moderate

Regions: Banff Yoho Kootenay.

We expect a natural avalanche cycle to occur in the alpine overnight Friday and into Saturday. Minimize your exposure to large alpine slopes and watch for small wind loaded slopes at lower elevations.

Weather Forecast

10-20cm of snow is forecast for Saturday in most areas with very strong alpine winds out of the West. Temperatures will gradually drop into the -10 to -15'C range as the weather begins to clear late on Saturday. Light flurries and moderate West winds are expected for Sunday.

Snowpack Summary

New wind slabs forming in the alpine and tree line areas which are easy to trigger. The Jan 6 surface hoar/facet/sun crust layer, down 30-60cm, is becoming less reactive to skier triggering, however sudden collapse results persist on the Jan 6 and Dec 3 layers. Isolated whumphing on mid-pack facets/surface hoar have been observed this past week.

Avalanche Summary

Several new natural wind slab failures were observed Friday up to size 2 in the Lake Louise area as the winds began to increase and the temperatures warmed up. We expect a substantial increase in natural activity over the next 24 hours as the storm arrives.

Confidence

Intensity of incoming weather systems is uncertain on Saturday

Avalanche Problems

Wind Slabs

10-20 cm of new snow is expected by Saturday accompanied by strong West winds. This will result in rapid loading of lee slopes and a substantial increase in natural avalanche activity especially in alpine areas.

If triggered the wind slabs may step down to deeper layers resulting in large avalanches.Avoid avalanche terrain during periods of heavy loading from new snow and wind.

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

Elevations: Alpine, Treeline.

Likelihood: Very Likely

Expected Size: 1 - 3

Loose Dry

The new snow and wind will cause loose dry avalanches to occur in alpine areas. These loose dry sluffs have potential to trigger larger avalanches below. Ice climbers in particular should avoid areas exposed to sluffing over the next couple of days.

The new snow will require several days to settle and stabilize.Avoid travelling under cliffs that are exposed to sluffing from above.

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

Elevations: Alpine.

Likelihood: Likely - Very Likely

Expected Size: 1 - 2

Persistent Slabs

An average of 30-60 cm overlies the Jan 6 layer of surface hoar, facets and sun crust. Test results on this layer show it has become stubborn to trigger, but potential for wide propagation remains. The new snow will increase the likelihood of this.

Avoid open slopes and convex rolls where buried surface hoar may be preserved.Use careful route-finding and stick to moderate slope angles with low consequences

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible - Likely

Expected Size: 2 - 3