Avalanche Forecast

Issued: Jan 14th, 2019 5:13PM

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.

Another day of temperature inversions and solar heating will keep slabs sensitive to failure on Tuesday. While some areas in this region have a deeper snowpack that is gaining strength, others do not: treat thin areas with increased caution.

Summary

Weather Forecast

Continued warm temperatures and sun are expected Tuesday as the temperature inversion continues . Winds that have been in the moderate range out of the West are forecast to diminish through to Wednesday. Cooling is expected on Wednesday increasing cloud. Trace amounts of snow can be expected Thursday.

Snowpack Summary

New solar crusts steep South and West slopes. Extensive wind effect in the alpine, less so 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 just above the ground.

Avalanche Summary

A size 3 slab failed on the south aspect of Mt Fairview sometime during the last couple days of temperature inversions 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. There were 2 sz 2 loose wet avalanches observed on a field trip to Hamilton Lake at 2400m west aspect.

Confidence

Due to the number of field observations

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, a thick layer of facets sits just below the Dec 10 layer which is about 80cm deep.

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

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

Possible

Expected Size

1 - 2

Valid until: Jan 15th, 2019 4:00PM