Parks Canada marcus waring, Parks Canada

Waterton Lakes National Park Avalanche Forecast

Dec 27th, 2019 4:00PM

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

Natural activity has tapered off but the potential for large avalanches running to the valley bottom remains. These could be triggered by cornices, small avalanches or humans in the wrong spot.

Summary

Weather Forecast

Saturday- Sunny with cloudy periods. West  wind 20-40km/h with gusts up to 60km/h.  Freezing Level valley bottom.

Sunday-  Flurries throughout the day. 1-5 cm of accumulation. Freezing Level 1300m. Moderate West -SW winds

Monday-  A mix of Sun and Cloud. Freezing Level valley bottom. Moderate West winds.

Snowpack Summary

The snowpack is thin below 1800m and capped by a met freeze crust. Above 1800m, 85-120cm of snow from last weeks storm sits on top of a weak facet/crust combo. The front ranges hold a thinner, more wind affected, snowpack.

Avalanche Summary

A widespread natural cycle occurred last weekend, with avalanches to size 2 in the storm snow and some larger ones failing on deep persistent weak layers. A size 3 natural avalanche occurred on Mt Bertha Sunday Dec 22 covering the Bertha Falls trail in debris, and a similar avalanche was seen on Mt. Crandell.

Confidence

Due to the number of field observations

Problems

Persistent Slabs

An icon showing Persistent Slabs

Likelihood

Possible

Expected Size

2 - 3

As natural activity on this layer begins to slow down, it is tempting to believe the problem has passed. This layer could still be triggered by people in thinner snowpack areas, or by large triggers including cornices or smaller avalanches.

  • Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.
  • Use conservative route selection, choose moderate angled and supported terrain with low consequence.

Aspects:

All aspects.

Elevations:

Alpine, Treeline.

Wind Slabs

An icon showing Wind Slabs

Likelihood

Possible

Expected Size

1 - 2

Wind slabs will be thicker and more reactive the higher you go. Snow amounts increase dramatically above 1800m.

  • Use caution in lee areas in the alpine and treeline. Recent storm snow has formed wind slabs.
  • If triggered the wind slabs may step down to deeper layers resulting in large avalanches.

Aspects:

North, North East, East, South East, South, North West.

Elevations:

Alpine, Treeline.

Valid until: Dec 30th, 2019 4:00PM