Avalanche Forecast

Issued: Dec 27th, 2013 4:00PM

The alpine rating is considerable, the treeline rating is moderate, and the below treeline rating is low. Known problems include Deep Persistent Slabs and Wind Slabs.

Grant Statham, Parks Canada

Banff Yoho Kootenay.

Conditions are extremely variable from west to east. The Yoho side of the forecast region has 15 cm of recent powder snow on the surface, while the Lake Louise side of the region is a windswept barren. Tonight's cold front should deposit 5-15 cm.

Summary

Weather Forecast

The passing cold front tonight will bring 5-15cm of snow accompanied by NW winds and cooling temperatures. Saturday and Sunday will bring flurries with continued moderate NW winds and moderate temperatures.

Snowpack Summary

10-15cm of recent snow has fallen west of the divide. This sits on a supportive but weak mid-pack over weak basal facets. On the East side of the divide strong West winds have stripped all windward slopes. Lee and cross loaded gullies have a mix of hard and soft wind slabs over a weak shallow base.

Avalanche Summary

A size 2 explosive triggered avalanche on a NE alpine feature at Lake Louise slide on the ground. A few natural loose snow avalanches up to size 2 out of very steep rocky alpine terrain were also observed in the Emerald Lake area.

Confidence

Problems

Deep Persistent Slabs

At this time all steep slopes have the potential to step down to the basal facets and result in large avalanches. The snow depth is quite variable across the forecast region, and triggering is most likely in shallow areas. Avoid starting zones.

Choose well supported terrain without convexities.Avoid steep, open slopes.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

2 - 3

Wind Slabs

Thin windslabs 15-20 cm deep are possible from leeward areas that will become loaded with the overnight snowfall that is forecast. Test on adjacent terrain features to check how much windslab has formed overnight.

Use caution in lee areas in the alpine. Recent wind loading have created wind slabs.Avoid convexities or areas with a thin or variable snowpack.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Valid until: Dec 28th, 2013 4:00PM