Avalanche Forecast

Issued: Feb 14th, 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.

tim haggarty, Parks Canada

Banff Yoho Kootenay.

Strong winds combined with the recent snowfall will keep the avalanche hazard elevated. Continued caution and conservative terrain selection is advised following the recent human triggered avalanches on the persistent weak layer.

Summary

Weather Forecast

A strong northwest flow sets up a very active week of weather ahead. We should see 5-10 cm of snow across the region by Monday evening with temperatures from -5 to -10C and strong (50-70 km/hr) westerly winds. This pattern of short bursts of 5 cm snowfalls looks to continue through the week.

Snowpack Summary

Fresh windslabs and new cornice growth in the alpine with 10 to 25cm 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 entire lower snowpack is facetted and quite weak, especially in shallower areas.

Avalanche Summary

Some human triggered windslabs were reported today in alpine areas. A few close calls in the last week. Friday, a group of 8 triggered a size 2 just left of the regular final approach slope to Bow Hut at 2400m on a NE aspect that was 40-80cm deep (Jan 6th layer), and ran 350m. This event caught 3, fully burying 1, and partially burying 2 more.

Confidence

Problems

Persistent Slabs

Numerous reports of avalanches triggered on the Jan 6 layer over the last 5 days (less reactive below treeline). In thinner areas, isolated avalanches have been seen to scrub to ground. Less natural activity noted today due to cooler temperatures.

Avoid paths that have not avalanched recently.Avoid areas with overhead hazard.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

2 - 3

Wind Slabs

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

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

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

Elevations: Alpine.

Likelihood

Likely

Expected Size

1 - 2

Valid until: Feb 15th, 2016 4:00PM