Avalanche Forecast

Issued: Dec 20th, 2016 4:00PM

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

jonas hoke, Parks Canada

Waterton Lakes.

Good skiing can be found in sheltered areas. Be cautious as you transition into more exposed terrain, previous stiff Winds Slabs may be difficult to detect under the more recent snow.

Summary

Weather Forecast

Ongoing Westerly flow giving continued warm temps (daytime highs above freezing at valley bottom) and strong to extreme winds through Thursday. The arrival of a cold front on Friday will give cooling temps and the onset of a snowfall that is supposed to last through the Christmas weekend.

Snowpack Summary

In Eastern areas, strong W winds have scoured windward slopes and created hard Wind Slabs over facets. Closer to the divide, strong west winds are moving 25cm of new snow into fresh Wind Slabs. These, and older wind slabs, overlie a faceted mid snowpack. The lower snowpack while well consolidated in deeper areas, may be facetted in shallow sites.

Avalanche Summary

Poor visibility due to ongoing strong to extreme winds has limited the opportunity for observations. Nearby operations have reported several explosive and skier triggered avalanches up to size 3.0 in stiff Wind Slab failing on previously facetted surfaces and on the ground in shallow snowpack areas.

Confidence

Due to the number of field observations

Problems

Wind Slabs

Use caution in lee areas in the alpine and treeline. Recent storm snow has formed wind slabs.Avoid cross loaded features.

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

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 2

Persistent Slabs

Be aware of the potential for wide propagations.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, Treeline.

Likelihood

Possible - Likely

Expected Size

2 - 3

Loose Dry

Use caution above cliffs where small avalanches may have severe consequences.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 1

Valid until: Dec 23rd, 2016 4:00PM