Avalanche Forecast

Issued: Apr 7th, 2014 4:05PM

The alpine rating is considerable, the treeline rating is considerable, and the below treeline rating is moderate. Known problems include Deep Persistent Slabs, Loose Wet and Cornices.

conrad janzen, Parks Canada

Banff Yoho Kootenay.

The first major warm up of the spring season is occurring right now accompanied by strong winds. This is a time to travel cautiously as we expect avalanche activity to increase and we may start to see failures on our deep persistent weak layers.

Summary

Weather Forecast

Strong SW winds, 5-15cms of snow, and rising freezing levels up to 2500m are forecast for Tuesday. Wednesday should see freezing levels drop back down to valley bottom with continued strong winds, cloudy weather and snow flurries. Thursday is a mix of sun and cloud and daytime freezing levels up to 2100m.

Snowpack Summary

Moist snow to 2000m on all aspects and to ridge top on solar aspects. Thin wind slabs in open areas. Western areas such as Emerald and Field have a deep and stable snowpack. The Lake Louise, Hwy 93 N, & Sunshine areas have a weaker snowpack and we are still getting easy to moderate sudden collapse results on the basal depth hoar in some areas.

Avalanche Summary

Loose wet sluffs observed in steep terrain on all aspects below 2000m and on solar aspects to ridge tops. Natural cornice failures have occurred in the last 48hrs creating slab avalanches to size 2. Kananaskis had a skier accidental yesterday in a thin snowpack area failing on the basal facets. We expect avalanche activity to increase tomorrow.

Confidence

Intensity of incoming weather systems is uncertain on Tuesday

Problems

Deep Persistent Slabs

With warming temperatures we expect to see an increase in avalanche activity on our deep facet layers especially in thinner snowpack areas or in places where a cornice fall could act as a large trigger. Minimize exposure to large slopes.

Use conservative route selection, choose moderate angled and supported terrain with low consequence.Avoid shallow snowpack areas where triggering is more likely.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

2 - 3

Loose Wet

Moist surface sluffing and small wet slabs are likely on all aspects and elevations as freezing levels climb on Tuesday. Stick to mellow terrain as even a small wet slide can be very powerful.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Very Likely

Expected Size

1 - 2

Cornices

Several cornice failures have occurred in the region over the last couple days. These can act as large triggers and cause failures on the basal facets. Warm temperatures and strong winds will cause this hazard to increase over the next few days.

Extra caution needed around cornices with current conditions.Cornices become weak with daytime heating, so travel early on exposed slopes.

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

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 2

Valid until: Apr 8th, 2014 4:00PM