Avalanche Forecast

Issued: Dec 19th, 2018 4:00PM

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

adam greenberg, Parks Canada

Waterton Lakes.

An additional 20-30cm of snow has fallen, and more is forecast for Thursday. Choose conservative terrain and evaluate the lower layers in the snowpack carefully.

Summary

Weather Forecast

Thursday: 15cm of snow along the divide with moderate to strong windsFriday: Mainly cloudy with scattered flurries and cooling temperatures down to -15 overnight. Winds moderate gusting strong.Saturday: Mainly cloudy with isolated flurries.

Snowpack Summary

The snowpack in Waterton is highly variable, but you can count on a weaker structure along the divide where another 20-30cm of recent storm snow on Tuesday has formed windslabs on lee slopes which are sitting on a weak snowpack consisting of old windslabs, facets and crusts.

Avalanche Summary

As of Wednesday morning, one size 2 skier accidental was reported on Monday running on the basal facets.

Confidence

Forecast snowfall amounts are uncertain on Thursday

Problems

Wind Slabs

New windslabs have formed with 20-30cm of new snow along the divide. Continued snow and wind Thursday night will continue to build slabs.

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

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Deep Persistent Slabs

New snow has increase the load on deep weak layers. This loading is likely to continue on Thursday Night with continued snowfall, increasing the potential for human triggering.

Be aware of thin areas that may propogate to deeper instabilites.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

1.5 - 2.5

Valid until: Dec 22nd, 2018 4:00PM