Avalanche Forecast

Issued: Feb 18th, 2016 4:00PM

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

stephen holeczi, Parks Canada

Banff Yoho Kootenay.

Avalanche sightings and/or close calls are still occurring on a daily basis. Cooling temperatures will take some time to start settling down the avalanche activity. It will be some time before we have confidence in the current snowpack. SH

Summary

Weather Forecast

A cooling into Friday with freezing levels staying at valley bottoms and alpine temperatures in the -10 to -12 range.Â A short pulse currently happening Thursday afternoon is forecast to input another 10cm with moderate to strong West winds at upper elevations.Â Cooler temps, light winds and minimal amounts of snow in the current 3 day forecast.

Snowpack Summary

Fresh windslabs and cornice growth in the alpine with 15 to 35 cm of recent snow and west winds. A 50-100 cm slab overlies the January 6th weak layer of surface hoar, facets and sun crust and snowpack tests indicate an unstable bond between the two. The lower snowpack is facetted and quite weak in thinner areas (<1.5m) and settled in thicker areas.

Avalanche Summary

There have been many close calls in the last week indicating that human triggering remains likely in many areas. Today with warming temperatures there were many loose wet or slab avalanches to size 2 out of steep terrain along the divide, and a large natural avalanche out of the National Geographics in the Lake Louise backcountry.

Confidence

Freezing levels are uncertain on Friday

Problems

Persistent Slabs

50-100 cm of snow overlies the Jan 6th layer of surface hoar, facets and sun crust. Numerous reports of avalanches triggered on this layer over the last week show that it is active. In thinner areas, isolated avalanches have scrubbed to ground.

Avoid paths that have not avalanched recently.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

2 - 3

Wind Slabs

Be mindful of cross loaded features and the lees of ridges where moderate to strong W winds have recently formed windslabs 10-40+ cm thick. If triggered, there is potential to step down to the persistent weak layer and to ground in thin areas.

Use caution in lee areas. Recent wind loading has created wind slabs.If triggered the wind slabs may step down to deeper layers resulting in large avalanches.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Valid until: Feb 19th, 2016 4:00PM