Avalanche Forecast

Issued: Jan 15th, 2019 4:00PM

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

tim haggarty, Parks Canada

Little Yoho.

While some areas in this region have a deeper snowpack that is gaining strength, others do not. Investigate the snow and treat thin areas with increased caution.

Summary

Weather Forecast

A cooling trend will begin as the inversion breaks down midday Wednesday. Winds will remain light and West to SW. Temps should drop Wednesday to -10C at 2000m and stay there through Thursday. As clouds build from pacific moisture moving in Thursday, expect trace amounts of snow to bury our current surface hoar, suncrust and wind effected surfaces.

Snowpack Summary

Solar crusts on some steep SE to West slopes at TL. Extensive wind effect in the alpine, less at treeline. In thick snowpack areas, the Dec 10th weak layer of facets is now down 100-150cm with a stronger snowpack below. In thin snowpack areas, there is little separation between Dec 10 and the weak depth hoar/ facets sitting 40 cm above the ground

Avalanche Summary

No field trip today and no reports of avalanches. A size 3 slab failed on the south aspect of Mt Fairview sometime during the weekend during the temperature inversion and clear skies. The crown was 70cm to 1m deep and over 1000m wide. The slide ran up the other side of the valley below Sheol. A good example of the deep persistent slab problem.

Confidence

Problems

Persistent Slabs

In deeper snowpack locations the Dec 10 layer is a thin, separated, layer of facets about 120cm deep which is becoming less of a problem. In thinner areas however, Dec 10 is only about 80cm deep and has a thick, weak, facet layer siting just below.

Be aware of the potential for wide propagations which could result in large avalanches.Convex features and steep unsupported slopes will be most prone to triggering.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

2 - 3

Wind Slabs

South and West winds built these slabs over the last week. While these slabs are becoming old, they are still worthy of respect, especially while the warm conditions continue.

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

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

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

1 - 2

Valid until: Jan 16th, 2019 4:00PM