Avalanche Forecast

Issued: Feb 16th, 2015 4:00PM

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

ian jackson, Parks Canada

Banff Yoho Kootenay.

Natural activity is tapering and the new snow and bluebird weather makes everything looks so tempting. Do the smart thing and resist temptation to step into bigger terrain as conditions are still prime for human triggering!

Summary

Weather Forecast

A ridge of high pressure is sitting above us. We can expect pleasant spring weather on Tues and Wed with light alpine winds, cool overnight temperatures (-10/ -15) and minimal solar effect on the snowpack despite the sunny skies. Winds should pick up to moderate from the West on Wed PM and we may see some light snow (5-10cm's) overnight Wed.

Snowpack Summary

Some wind effect in open areas above tree line. Temperature crust present below 1800m. 60-70cm of well settled snow from recent storms and warm temperatures sits over weak facets and depth hoar at the bottom of the snowpack. A snow pit done at 2350m near Cirque Peak on Saturday demonstrates the snowpack layering common in the forecast region.

Avalanche Summary

Another skier accidental: size 2 in the Sunshine Backcountry on Sunday. One new avalanche reported on Monday: a size 2.5 naturally triggered slab on a SW aspect at 2500m in the Mt. Assiniboine area. Limited observations today, however, we are just coming out of a natural avalanche cycle on Saturday, and conditions are still touchy.

Confidence

The weather pattern is stable

Problems

Deep Persistent Slabs

The base of the snowpack remains weak due to the presence of basal depth hoar and facets. Avalanches have been occurring on this layer daily: either failing on this layer, or stepping down to this layer with wide propagations.

Use conservative route selection, choose moderate angled and supported terrain with low consequence.Be aware of thin areas that may propogate to deeper instabilites.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

2 - 3

Wind Slabs

Winds from both the SW and NW have formed fresh wind slabs in open areas above tree line. These are settling out but can still be triggered and may step down to the basal weak layers.

Use caution in lee areas. Recent wind loading have 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

Unlikely - Possible

Expected Size

1 - 2

Valid until: Feb 17th, 2015 4:00PM