Avalanche Forecast

Issued: Feb 2nd, 2016 4:00PM

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

snow safety, Parks Canada

Banff Yoho Kootenay.

By definition the hazard is moderate treeline and below, however the potential still exists for human triggering of large avalanches in open terrain at these elevations. JH

Summary

Weather Forecast

Slight warming (highs of -7 by friday), increasing westerly wind(moderate on Wednesday) cloudy skies andÂ light flurries are forecast through the rest of the week.

Snowpack Summary

Wind slabs in alpine and tree line areas. 30-60cm of snow over the Jan 6 surface hoar/facet/sun crust layer, which is becoming less reactive to skier triggering. Sudden collapse results persist on the Jan 6 and Dec 3 layers in the Kootenay region. Isolated whumphing on mid-pack facets/surface hoar today.

Avalanche Summary

Visitor Safety was able to trigger a size 1.5 wind slab on a SE steep alpine feature on Monday near Observation Peak. A large natural cornice collapse also occurred Monday in the Sunshine backcountry on Quartz Ridge. Lots of evidence of the previous widespread natural avalanche cycle up to size 3 on all aspects with some very large propagations.

Confidence

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.

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

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 is still in the range of human triggering with potential for failures to step down into deeper layers and result in large avalanches.

Use careful route-finding and stick to moderate slope angles with low consequencesAvoid open slopes and convex rolls where buried surface hoar may be preserved.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

2 - 3

Valid until: Feb 3rd, 2016 4:00PM