Avalanche Forecast

Issued: Jan 29th, 2016 5:02PM

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.

tim haggarty, Parks Canada

Banff Yoho Kootenay.

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

Summary

Weather Forecast

Following a some clear skies on Friday we expect more unsettled conditions through the weekend. Flurries can be expected Saturday with alpine temperatures from -10 to -14 and light to moderate West winds. Mainly cloudy skies for Sunday with alpine temperatures cooling to -16 overnight and winds shifting to the NW and backing to light.

Snowpack Summary

Thursday's storm added 10 to 25cm with strong SW winds and freezing levels to approx. 1900m. Widespread unstable slabs exist with 30 to 100cm sitting on weak faceted crystals and surface hoar. Wet conditions BTL yesterday refroze overnight and crusts will now help hold things together where they are of sufficient thickness (below about 1900m).

Avalanche Summary

With today's clearing an extensive cycle of natural avalanches to size 3 were observed mainly above 1900m centered along highway 93N. Slabs propagated several hundred meters wide and over 40cm deep on many of the open slopes.While less activity has been seen in other parts of the region, conditions are ripe for human triggering and large avalanches

Confidence

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 exist at upper elevations, avalanches have the potential to run a long distance.

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

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 3

Persistent Slabs

Close to 50 cm of settled snow now overlies the Jan 4 layer of surface hoar and facets. While crusts may hold things together below about 1900m be cautious above this where human triggering is likely and natural activity is quite possible.

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

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

2 - 3

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