Archived

Avalanche Forecast

Feb 3rd, 2016–Feb 4th, 2016

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

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

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

Regions: Banff Yoho Kootenay.

While human triggering of avalanches is becoming less likely, the potential for wide propagation still exists, be cautious in open terrain. JH

Weather Forecast

Slight warming (highs of -7 at Bow Summit on Thursday), increasing west/northwest wind (Moderate to Strong on Thursday), cloudy skies and light flurries are forecast through the rest of the week.

Snowpack Summary

Wind slabs in alpine and tree line areas are now stubborn to trigger. The Jan 6 surface hoar/facet/sun crust layer, down 30-60cm, has becoming less reactive to skier triggering, however sudden collapse results persist on both the Jan 6 and Dec 3 layers. Isolated whumphing on mid-pack facets/surface hoar were observed yesterday.

Avalanche Summary

Avalanche control using explosives at local ski resorts on Tuesday produced windslab up to size 1.5, and an isolated size 2.0 persistent slab avalanche on a West aspect in the alpine. Lots of evidence of the previous widespread natural avalanche cycle up to size 3 on all aspects with some very large propagations.

Confidence

Avalanche Problems

Wind Slabs

Previous wind has built soft slabs 30 to 50cm deep in alpine and tree line lee areas. Although these slabs are slowly becoming more difficult to trigger, human triggering is still possible.

Avoid steep lee and cross-loaded featuresIf triggered the wind slabs may step down to deeper layers resulting in large avalanches.

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

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1 - 2

Persistent Slabs

30-60 cm of snow 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 the potential for wide propagation remains.

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

Expected Size: 2 - 3