Avalanche Forecast

Issued: Jan 11th, 2019 4:09PM

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

tim haggarty, Parks Canada

Little Yoho.

Recent windslabs are becoming the main concern in Little Yoho's fatter snowpack areas. There are however many thinner snowpack areas here where triggering slabs over basal facets are a big concern: Field Ice Climbers beware.

Summary

Weather Forecast

Freezing levels are forecast to approach 2200m daily through Monday which may keep slabs sensitive to human triggering. Watch for potential temperature inversions. Moderate to Strong SW winds should start to diminish Saturday and it looks to be cloudy near the divide until Monday when the potential for solar inputs looks likely.

Snowpack Summary

Snowfall since Jan2 has been redistributed by southwest winds yielding extensive wind effect in the alpine. 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

A group just outside of the Lake Louise ski area above the Pika Flats at treeline triggered a sz 2 slab 80cm deep failing 40m wide and running 200m on a SW aspect today. The snow safety team at Sunshine Village saw several windslabs fail in the last 24 hrs one of which scrubbed to the ground and produced a large avalanche off of the Monarch.

Confidence

Freezing levels are uncertain on Saturday

Problems

Wind Slabs

Moderate to strong SW winds have moved a significant amount of snow over the last three days. Expect widespread wind effect in the alpine and get your guard up as you enter open areas at treeline.

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

Likely

Expected Size

1 - 2.5

Persistent Slabs

The Dec.10 layer of facets and some surface hoar are down 130+cm at treeline in the fatter snowpack areas more typical in this region. The sensitivity of this layer seems more concerning at lower elevations but few observations have been made so far

Convex features and steep unsupported slopes will be most prone to triggering.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

2 - 3.5

Valid until: Jan 12th, 2019 4:00PM