Avalanche Forecast

Issued: Jan 21st, 2019 4:00PM

The alpine rating is moderate, 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.

Keep an eye on actual snowfall amounts on Wednesday. Strong winds and incoming snow has the potential to overload buried surface hoar and suncrusts.

Summary

Weather Forecast

Tuesday: Cloudy with scattered flurries. Snowfall amounts 4cm. Alpine high -10, strong SW winds.Wednesday: Periods of snow. There is disagreement on amounts in the models but we may see up to 15cm. Moderate W winds, freezing level 1300m.Thursday: Cloudy with isolated flurries. Freezing level down to valley bottom with moderate W winds.

Snowpack Summary

25cm of recently wind affected snow is sitting on either a suncrust below 2000m on solar aspects or spotty surface hoar in sheltered areas between 1600 and 1900m. This may be a problem layer as we see more snow this week. The midpack is strong in deep snowpack areas, but the facets lingering at the bottom remain a concern in thinner areas.

Avalanche Summary

A forecasting trip up the Akamina parkway revealed several small loose dry avalanches out of steep rocky terrain. A skier in the Fernie backcountry triggered an avalanche failing on the same surface hoar layer we are seeing in the park but was able to ski out of it. With up to 20cm of snow in the forecast we may see similar activity on this layer.

Confidence

Intensity of incoming weather systems is uncertain on Wednesday

Problems

Wind Slabs

Wind Slabs will continue to build over a crust / surface hoar layer and may propagate farther than expected. Dig down and investigate the bond of new snow before committing to your line.

Avoid open slopes and convex rolls at and below treeline where buried surface hoar may be preserved.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1.5 - 2.5

Deep Persistent Slabs

This layer likely requires a large trigger. Be cautious when transitioning from thick to thin snowpack areas

Avoid steep convexities or areas with a thin or variable snowpack.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

2 - 3

Valid until: Jan 24th, 2019 4:00PM