Avalanche Forecast

Issued: Mar 24th, 2021 4:00PM

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

Avalanche Canada ahanna, Avalanche Canada

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Previously formed wind slabs may remain reactive to human triggers. Look for signs of instability in wind affected snow as you gain elevation.

Summary

Confidence

Moderate -

Weather Forecast

Wednesday night: Flurries bringing a trace of snow. Westerly wind easing to light. Alpine temperatures around -7. Freezing level valley bottom.

Thursday: Mostly cloudy with flurries bringing a trace. Light wind. Alpine high temperatures around -5. Freezing level 1700 m.

Friday: Mix of sun and cloud. Light to moderate westerly wind. Alpine high temperatures around -2. Freezing level 1800 m.

Saturday: Sunny. Moderate westerly wind. Alpine high temperatures around 0. Freezing level 2400 m.

Avalanche Summary

On Monday and Tuesday, we received a few reports of size 1 natural and explosive-triggered wind slabs in steep, unsupported alpine features in the south of the region where recent snowfall amounts have been greatest.

Snowpack Summary

20-30 cm of new snow has been accumulating incrementally over recent days on top of wind affected surfaces in the alpine and refrozen crust lower down after light rain recently wet the snow surface below about 1700 metres. This new snow is most likely being blown around by strong winds forecast overnight Tuesday and into Monday morning, forming fresh wind slabs in lee terrain features at upper elevations.

Around 30 to 60 cm of snow sits above a layer of sugary faceted grains that were buried in mid-February. In some areas, there may be an old layer of feathery surface hoar or facets from late January down 50 to 80 cm deep. There have been no reported avalanches on either of these layers in the region since March 9th in the Crowsnest.

The mid pack is firm and well settled. Some faceted snow and a decomposing melt-freeze crust can be found near the base of the snowpack.

Terrain and Travel

  • Be alert to conditions that change with elevation.
  • Be careful with wind slabs, especially in steep, unsupported and/or convex terrain features.
  • Watch for signs of instability like whumpfing, hollow sounds, shooting cracks or recent avalanches.

Problems

Wind Slabs

An icon showing Wind Slabs

Watch for wind loaded pockets in lee terrain features such as beneath ridge crests and roll-overs.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 1.5

Valid until: Mar 25th, 2021 4:00PM