Avalanche Forecast

Issued: Mar 25th, 2020 4:00PM

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

Avalanche Canada cgarritty, Avalanche Canada

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New snow and elevated winds will introduce fresh surface instabilities to the region.

Summary

Confidence

Low - Forecast snowfall amounts are uncertain. Uncertainty is due to the limited number of field observations.

Weather Forecast

Wednesday night: Becoming cloudy with flurries bringing 5-10 cm of new snow, increasing in the morning. Moderate to strong west winds.

Thursday: Cloudy with continuing snowfall bringing 10-15 cm of new snow, easing overnight. Moderate to strong southwest winds. Alpine high temperatures around -5.

Friday: Cloudy with isolated flurries and up to 5 cm of new snow, increasing overnight. Moderate to strong southwest winds, increasing overnight. Alpine high temperatures around -5.

Saturday: Cloudy with continuing flurries bringing 5-10 cm of new snow, continuing overnight. Moderate to strong southwest wind. Alpine high temperatures around -5.

Avalanche Summary

A recent large (size 2.5) natural glide slab release was observed on Tuesday. The debris from the release overran the John Little Falls hiking trail. 

Natural glide slab activity has been a regular occurence during recent periods of daytime warming, reinforcing the importance of avoiding glide cracks and areas exposed glide slab hazards.

Snowpack Summary

Surface conditions over the region are likely a mix of recent wind slabs and wind-affected snow as well as melt freeze crust on south aspects and below about 1100 metres.

A layer of surface hoar crystals is buried around 30 to 60 cm in sheltered areas at and below treeline, shallow enough for human triggering on steep slopes where it is preserved. Recent observations of this layer are lacking.

An early-season layer of faceted grains and a melt-freeze crust can likely be found near the base of the snowpack at high elevations. A large load, such as a large cornice fall, may have potential to trigger it.

Terrain and Travel

  • Storm slab size and sensitivity to triggering will likely increase through the day.

Problems

Storm Slabs

An icon showing Storm Slabs

New snow falling over Wednesday night and Thursday will introduce a fresh surface instability to the region. Forecast amounts vary, meaning hazards may range from small wind slabs forming on leeward slopes to more widespread storm slabs affecting most avalanche terrain.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 2

Persistent Slabs

An icon showing Persistent Slabs

A weak layer of surface hoar crystals is buried around 30 to 60 cm deep in sheltered, shady terrain around treeline. It was reactive to both human and natural triggers last week and there is uncertainty about whether it is still a problem.

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

Elevations: Treeline.

Likelihood

Unlikely - Possible

Expected Size

1.5 - 2.5

Valid until: Mar 26th, 2020 5:00PM