Avalanche Forecast

Issued: Dec 29th, 2016 4:25PM

The alpine rating is high, the treeline rating is considerable, and the below treeline rating is low. Known problems include Persistent Slabs, Wind Slabs and Loose Dry.

grant statham, Parks Canada

Banff Yoho Kootenay.

Heads up out there - lots of fresh snow combined with strong winds over the last week has elevated the avalanche hazard. The only thing keeping us from a full blown avalanche cycle is the cold air - be aware that human triggering is very likely.

Summary

Weather Forecast

Strong westerly flow continues but the main pulse of snowfall should taper by Friday morning. Friday looks like a mix of sun and clouds with winds tapering slightly and temperatures remaining cool (below -10). Another round of snow is expected for Saturday.

Snowpack Summary

Up to 50 cm of storm snow has been blown into widespread wind slabs by consistent, strong westerly winds over the past week. These unstable slabs overlie an interface of small facets, buried on Dec 19, and we expect avalanches can be easily triggered by people. Natural activity is expected over the next 24-hours in alpine areas.

Avalanche Summary

Poor visibility today, but the ski areas reported only small soft slabs within the recent snow inside the ski area boundary.

Confidence

Due to the number of field observations

Problems

Persistent Slabs

Wind slabs up to 60cm from last week sit on top of a weak layer of facets (Dec 19 layer). This interface is poorly bonded, resulting in many recent avalanches. This weak, faceted layer will persist for some time.

Be aware of the potential for wide propagations due to the presence of hard windslabs.

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

2 - 3

Wind Slabs

Thick wind slabs have formed in the lees of alpine features. These will be touchy in the short term with the current snow and wind forecast. Once initiated, they may trigger a persistent slab on the Dec.19th facets.

If triggered the storm/wind slabs may step down to deeper layers resulting in large avalanches.

Aspects: North, North East, East.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 2

Loose Dry

ICE CLIMBERS - watch out for large sluff in gullied routes as there is a lot of loose snow being blow around by the wind.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 2

Valid until: Dec 30th, 2016 4:00PM