Avalanche Forecast

Issued: Jan 30th, 2016 4:06PM

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

conrad janzen, Parks Canada

Banff Yoho Kootenay.

Heads up! Climbers and skiers should manage their overhead exposure carefully and choose conservative terrain as large avalanches are likely at all elevations. Widespread touchy slabs are ripe for human triggering.

Summary

Weather Forecast

Light flurries can be expected Sunday in western regions of the forecast area with a mix of sun and cloud in other areas. Alpine temperatures will range from -10 to -15 with light winds out of the NW. A clearing trend is expected on Monday as alpine temperatures cool to -16 to -18 with continued light NW winds.

Snowpack Summary

Touchy wind slabs in alpine and treeline areas, and fragile new cornices in the alpine. 30-50 cm of snow sits over the Jan 6 surface hoar/facet layer and is reactive to skier triggering. We have experienced many large whumphs over the last several days with failures on both the Jan 6 surface hoar/facets, and in the mid pack facets below this layer.

Avalanche Summary

Several natural avalanches were observed Saturday up to size 2. This follows an extensive natural cycle of avalanches up to size 3 during the past 48 hours with slabs propagating up to several hundred meters and over 40cm deep on many slopes. Conditions remain ripe for human triggering and occasional large natural avalanches.

Confidence

Due to the number and quality of field observations

Problems

Wind Slabs

SW winds during the warm wet storm Thursday built soft slabs 50 to 100cm deep in lee areas and established fragile new growth on cornices. Although these slabs generally exist at upper elevations, avalanches have the potential to run a long distance.

Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.Avoid steep lee and cross-loaded features

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 3

Persistent Slabs

30-50 cm of settled snow overlies the Jan 6 layer of surface hoar and facets. This continues to be reactive to both human and explosive triggering with potential for failures to step down into deeper snowpack layers and result in large avalanches.

Avoid open slopes with any steepness over 30 degrees.Avoid open slopes and convex rolls at and below treeline where buried surface hoar may be preserved.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

2 - 3

Valid until: Jan 31st, 2016 4:00PM