Avalanche Forecast

Issued: Mar 3rd, 2018 4:00PM

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

conrad janzen, Parks Canada

Banff Yoho Kootenay.

10-20cm of storm snow has made for excellent skiing! Our main concerns are small buried wind slabs and sluffing in steep terrain. We removed the persistent slab problem because of a lack of activity on this layer, but the structural weakness remains.

Summary

Weather Forecast

A few more cm's of new snow are forecast for Saturday night and Sunday with continued light winds switching from E to SW overnight. Temperatures are forecast to remain cool (-5 to -15°C) depending on elevation with a slight increase Sunday afternoon.

Snowpack Summary

10-20 cm of storm snow with little wind effect sits over buried wind slabs in open areas at higher elevations, and over loose facets at lower elevations. Below this a firm mid-pack covers the Jan surface hoar layers that are rounding and inactive in tests. The deeper facet layers down 80-150 cm remain weak but are presently difficult to propagate.

Avalanche Summary

Small loose snow avalanches/sluffing has been reported in some steep treeline areas with the storm snow failing on the facets below and running a fair distance. A couple small buried wind slab failures have also been reported recently in steep terrain. The persistent weak layers have been inactive for two weeks and have been removed as a problem.

Confidence

Wind speed and direction is uncertain on Monday

Problems

Wind Slabs

Wind slabs covered by 10-20cm of loose snow exist in lee areas in the alpine. They have not been very easy to trigger, but do have potential to carry you into an undesirable location (cliffs/terrain traps) if they fail in steep terrain.

Be careful with wind loaded pockets, especially near ridge crests and roll-overs.

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

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 1.5

Loose Dry

10-20 cm of storm snow has fallen with little wind. In many places this sits over loose facets from the last cold snap and with any increase in wind, or skier triggering, we will see small sluffs traveling a long ways in steep terrain.

On steep slopes, pull over periodically or cut into a new line to manage sluffing.The volume of sluffing could knock you over; choose your climb carefully and belay when exposed.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 1.5

Valid until: Mar 4th, 2018 4:00PM